• mk5decode - to decode Mark5A data recorded in "512-8-2" mode;

• mk5decode - to decode Mark5A data recorded in "512-8-2" and "512-16-2" modes;

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="program to decode Mark5A data" date="1119653281" path="mk5decode.tgz" size="36281" user="VladKondratiev" version="1.2"}%

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="new version of mk5decode" date="1193794223" path="mk5decode.tgz" size="63002" user="VladKondratiev" version="1.3"}%

Please, read: If you used the programs, files or any other information from this page, we are asking you to acknowledge use of it, both by giving the web-address of this wiki-page and by referencing the paper: Kovalev, Y.Y., Ghigo, F., Kondratiev, V.I., Bartel, N., Soglasnov, V.A., Popov, M.V. 2005, ``Observing at the GBT with VLBA+Mark5A and VLBA+S2 backends'',GBT Commissioning Memo 236; available at _http://wiki.gb.nrao.edu/pub/Knowledge/GBTMemos/GBT_Mark5A_S2.pdf

Thank you!

-- VladKondratiev - 4 October 2007

We have tested GBT observing with VLBA+Mark5A and VLBA+S2 back-ends.

We have tested single-dish GBT observing with high temporal resolution utilizing VLBA+Mark5A and VLBA+S2 back-ends.

-- VladKondratiev - 29 Mar 2005

-- VladKondratiev - 24 June 2005

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="program to decode Mark5A data" date="1110221918" path="mk5decode.tgz" size="23098" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="program to decode Mark5A data" date="1119653281" path="mk5decode.tgz" size="36281" user="VladKondratiev" version="1.2"}%

• For best results one should use values +3.3359, +1, -1, -3.3359 in the VLBA bit-correspondence scheme as noted in VLBA memo No.5 by L.Kogan. Unfortunately, for now it is not implemented and we used more simple +3, +1, -1, -3 scheme. However, in our subsequent processing we changed the decoding values from +/- 1 and +/- 3 to real values that correspond to the current +/- sigma levels in accordance with the technique developed by Jenet & Anderson (1998). This technique is implemented in bitstat program. It can be used as for data correction as for just checking the percentage of bit-couples that give +3, +1, -1 or -3 values.

• For best results one should use values +3.3359, +1, -1, -3.3359 in the VLBA bit-correspondence scheme as noted in VLBA memo No.5 by L.Kogan. Unfortunately, for now it is not implemented and we used more simple +3, +1, -1, -3 scheme. However, in our subsequent processing we changed the decoding values from +/- 1 and +/- 3 to real values that correspond to the current +/- sigma levels in accordance with the technique developed by Jenet & Anderson (1998). This technique is implemented in bitstat program. It can be used for data correction as well as just for checking the percentage of bit-couples that give +3, +1, -1 or -3 values.

-- YuriKovalev - 7 June 2005

-- YuriKovalev - 13 June 2005

See GBT memo 236.

-- YuriKovalev - 30 Mar 2005

-- YuriKovalev - 7 June 2005

Summary:

Introduction

Both Mark5A ans S2 back ends are standard VLBI recording systems which are available in many radio observatories around the world. This makes the use of them relatively easy and reliable. They can be utilized not only for VLBI experiments but for any kind of experiment which calls for high temporal resolution. Particularly, for pulsar observing.

We have performed a test with GBT (February 5, 2005, 16:45 -- 20:00 UT, observations of two strong pulsars with well known parameters, PSR1937+21 and Crab pulsar) in order to check reliability of use in a single dish mode of available VLBA+Mark5A and VLBA+S2 GBT back ends. We have choosen to use pulsars in this test because they provide the best possibility to fine check parameters of the system used for hight temporal resolution observing.

Crab

-- YuriKovalev - 23 Feb 2005 -- VladKondratiev - 23 Feb 2005 -- VladKondratiev - 04 Mar 2005 -- VladKondratiev - 07 Mar 2005 -- VladKondratiev - 08 Mar 2005 -- VladKondratiev - 10 Mar 2005 -- VladKondratiev - 11 Mar 2005 -- VladKondratiev - 14 Mar 2005 -- VladKondratiev - 21 Mar 2005 -- VladKondratiev - 28 Mar 2005

-- YuriKovalev - 30 Mar 2005

-- VladKondratiev - 29 Mar 2005

%META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1112055951" path="meander.lcp.X.ps" size="3059427" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1112056013" path="meander.lcp.X.peak.ps" size="18857" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1112056062" path="meander.rcp.Z.ps" size="3078283" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1112056113" path="meander.rcp.Z.peak.ps" size="18838" user="VladKondratiev" version="1.3"}%

%META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1112139324" path="meander.lcp.X.ps" size="3098263" user="VladKondratiev" version="1.4"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1112139376" path="meander.lcp.X.peak.ps" size="18574" user="VladKondratiev" version="1.4"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1112139417" path="meander.rcp.Z.ps" size="3109524" user="VladKondratiev" version="1.4"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1112139464" path="meander.rcp.Z.peak.ps" size="18554" user="VladKondratiev" version="1.4"}%

During the most part of our observations we had noise-diode turned on. The switching frequency was 80 Hz, so the period is 12.5 ms. With this period we folded the noise-diode meander during of about 15.5 secs (1239 individual meander periods) for all sidebands in each polarization. Here are the examples for LCP-X (2084-2100 MHz) and RCP-Z (2052-2068 MHz). The averaged noise-diode amplitude in all frequency channels was 2.1 K. The average system temperature appeared to be of about 40 K. This value is higher than accepted value of about 25 K in our observing frequency. Anomalous significant peak is present at the rise edge of the noise-diode signal. Its fine structure are here: LCP-X, RCP-Z. The peak temperature is more that twice larger than our system temperature, i.e of about 125% (90K) for both LCP-X and RCP-Z with FWHM of about 120 ns.

During the most part of our observations we had noise-diode turned on. The switching frequency was 80 Hz, so the period is 12.5 ms. With this period we folded the noise-diode meander during of about 15.5 secs (1239 individual meander periods) for all sidebands in each polarization. Here are the examples for LCP-X (2084-2100 MHz) and RCP-Z (2052-2068 MHz). The averaged noise-diode amplitude in all frequency channels was 2.0 K. The average system temperature appeared to be of about 23 K. Anomalous significant peak is present at the rise edge of the noise-diode signal. Its fine structure are here: LCP-X, RCP-Z. The peak temperature is more that twice larger than our system temperature, i.e of about 125% (52K) for both LCP-X and RCP-Z with FWHM of about 120 ns.

%META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1112029766" path="meander.lcp.X.ps" size="3097858" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1112030307" path="meander.lcp.X.peak.ps" size="18307" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1112029930" path="meander.rcp.Z.ps" size="3103853" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1112030321" path="meander.rcp.Z.peak.ps" size="18317" user="VladKondratiev" version="1.2"}%

%META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1112055951" path="meander.lcp.X.ps" size="3059427" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1112056013" path="meander.lcp.X.peak.ps" size="18857" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1112056062" path="meander.rcp.Z.ps" size="3078283" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1112056113" path="meander.rcp.Z.peak.ps" size="18838" user="VladKondratiev" version="1.3"}%

%META:FILEATTACHMENT{name="mk5strongW.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel W" date="1112026962" path="mk5strongW.ps" size="19034" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongX.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel X" date="1112026992" path="mk5strongX.ps" size="19926" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongY.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Y" date="1112027032" path="mk5strongY.ps" size="19871" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongZ.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Z" date="1112027056" path="mk5strongZ.ps" size="20754" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="mk5strongW.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel W" date="1112056477" path="mk5strongW.ps" size="19630" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5strongX.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel X" date="1112056508" path="mk5strongX.ps" size="19132" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5strongY.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Y" date="1112056536" path="mk5strongY.ps" size="20158" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5strongZ.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Z" date="1112056572" path="mk5strongZ.ps" size="19636" user="VladKondratiev" version="1.2"}%

%META:FILEATTACHMENT{name="mk5_crab_W.ps" attr="" comment="Mk5 Crab GP example, channel W" date="1112031411" path="mk5_crab_W.ps" size="23323" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_X.ps" attr="" comment="Mk5 Crab GP example, channel X" date="1112031437" path="mk5_crab_X.ps" size="23355" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_Y.ps" attr="" comment="Mk5 Crab GP example, channel Y" date="1112031469" path="mk5_crab_Y.ps" size="23125" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_Z.ps" attr="" comment="Mk5 Crab GP example, channel Z" date="1112031494" path="mk5_crab_Z.ps" size="22645" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="mk5_crab_W.ps" attr="" comment="Mk5 Crab GP example, channel W" date="1112056228" path="mk5_crab_W.ps" size="23432" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5_crab_X.ps" attr="" comment="Mk5 Crab GP example, channel X" date="1112056258" path="mk5_crab_X.ps" size="23472" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5_crab_Y.ps" attr="" comment="Mk5 Crab GP example, channel Y" date="1112056288" path="mk5_crab_Y.ps" size="23238" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="mk5_crab_Z.ps" attr="" comment="Mk5 Crab GP example, channel Z" date="1112056312" path="mk5_crab_Z.ps" size="22760" user="VladKondratiev" version="1.2"}%

%META:FILEATTACHMENT{name="strongW.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112033791" path="strongW.ps" size="19493" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="strongX.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112033845" path="strongX.ps" size="21679" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="crab_s2_mk5_W.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112034031" path="crab_s2_mk5_W.ps" size="21152" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="crab_s2_mk5_X.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112034069" path="crab_s2_mk5_X.ps" size="21999" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="strongW.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112056417" path="strongW.ps" size="20435" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="strongX.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112056440" path="strongX.ps" size="20881" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="crab_s2_mk5_W.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112056364" path="crab_s2_mk5_W.ps" size="21266" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="crab_s2_mk5_X.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112056387" path="crab_s2_mk5_X.ps" size="22111" user="VladKondratiev" version="1.2"}%

Software

• mk5decode - to decode Mark5A data recorded in "512-8-2" mode;
• decoder - to decode S2 data;
• bitstat - to correct decoded files for bit-statistics and check the percentage of bit-couples;
• see - for binary data visualization.

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="decoding program" date="1110221918" path="mk5decode.tgz" size="23098" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="program to decode Mark5A data" date="1110221918" path="mk5decode.tgz" size="23098" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="see.tgz" attr="" comment="program for visualization of binary data" date="1112044878" path="see.tgz" size="65845" user="VladKondratiev" version="1.1"}%

• For best results one should use values +3.3359, +1, -1, -3.3359 in the VLBA bit-correspondence scheme as noted in VLBA memo No.5 by L.Kogan. Unfortunately, for now it is not implemented and we used more simple +3, +1, -1, -3 scheme.

• For best results one should use values +3.3359, +1, -1, -3.3359 in the VLBA bit-correspondence scheme as noted in VLBA memo No.5 by L.Kogan. Unfortunately, for now it is not implemented and we used more simple +3, +1, -1, -3 scheme. However, in our subsequent processing we changed the decoding values from +/- 1 and +/- 3 to real values that correspond to the current +/- sigma levels in accordance with the technique developed by Jenet & Anderson (1998). This technique is implemented in bitstat program. It can be used as for data correction as for just checking the percentage of bit-couples that give +3, +1, -1 or -3 values.

For decode our Mark5A data I wrote the program mk5decode. It decodes only the data recorded with mode "512-8-2", i.e

For decode our Mark5A data we wrote the program mk5decode. It decodes only the data recorded with mode "512-8-2", i.e

The phase characteristic curves were built for both polarizations based on Pcal harmonics phase: LCP, RCP. It is seen that phase showes linear pass within the sideband.

The amplitude of Pcal signal in our receiver bandpass for both polarizations: LCP, RCP. The average fine structure of one of the Pcal harmonics in LCP is here. The value 0 of relative frequency represents the frequency of 2070 MHz. The number of samples were averaged is 422. The frequency resolution is 3.81 Hz.

During the most part of our observations we had noise-diode turned on. The switching frequency was 80 Hz, so the period is 12.5 ms. With this period we folded the noise-diode meander during of about 15.5 secs (1239 individual meander periods) for all sidebands in each polarization. Here are the examples for LCP-X (2084-2100 MHz) and RCP-Z (2052-2068 MHz). The increasing of system temperature is of about 4.8% (1.2K) for LCP-X and 6% (1.5K) for RCP-Z that is in good agreement with expected values. But very significant peak was found in the rising edge of the noise-diode meander: LCP-X, RCP-Z. The peak temperature is more that twice larger than our system temperature, i.e 122% (55.4K) for LCP-X and 126.4% (56.6K) for RCP-Z with FWHM of about 120 ns.

The phase characteristic curves were built for both polarizations based on Pcal harmonics phase: LCP, RCP. There are shown together with S2 Pcal phase curves here.

Giant pulse from B1937+21 - the first one ever detected using VLBA Mark5A back-end: GP_lcp_2084-2100.ps

During the most part of our observations we had noise-diode turned on. The switching frequency was 80 Hz, so the period is 12.5 ms. With this period we folded the noise-diode meander during of about 15.5 secs (1239 individual meander periods) for all sidebands in each polarization. Here are the examples for LCP-X (2084-2100 MHz) and RCP-Z (2052-2068 MHz). The averaged noise-diode amplitude in all frequency channels was 2.1 K. The average system temperature appeared to be of about 40 K. This value is higher than accepted value of about 25 K in our observing frequency. Anomalous significant peak is present at the rise edge of the noise-diode signal. Its fine structure are here: LCP-X, RCP-Z. The peak temperature is more that twice larger than our system temperature, i.e of about 125% (90K) for both LCP-X and RCP-Z with FWHM of about 120 ns.

Giant pulse from B1937+21 - the first one ever detected using VLBA Mark5A back-end - in all Mk5 frequency channels: W, X, Y, Z. This pulse appeared to be the strongest one with peak flux density of about 2000 Jy (150 sigma).

Dispersion measure of the B1937+21 was measured to be 71.017 pc/cm^3.

Average profiles of regular pulses with phases of detected events: scan2 | scan3.

Average profiles of regular pulses for the B1937+21 with phases of detected events: scan2 | scan3. Flux density of average regular profile for the B1937+21 was found to be of about 65 mJy.

There were processed of about 2.5 min of the Crab data in Mk5 records.

Example of one of the Crab giant pulses in all frequency channels for both polarization: W, X, Y, Z. The values of flux densities are mainly determined by Crab Nebula background emission which was accepted as 710 Jy.

to be presented

The form of receiver bandpass from S2 data without interferences: S2-band.

The amplitude of Pcal signal in both S2 frequency channels is here.

The phase characteristic curves of phase calibration signal for both frequency channels in S2 are presented here. Also, there are shown together with Mark5 pcal phase curves here.

The strongest GP from B1937+21 from S2 data together with Mk5 data: 2100 - 2116 MHz, 2084 - 2100 MHz. The S2 & Mk5 profiles look very close to each other.

The profiles of one of the Crab giant pulses obtained from S2 and Mk5 data: 2100 - 2116 MHz, 2084 - 2100 MHz. Differences in profile shapes between S2 and Mk5 are caused by different values of DM were used in coherent dedispersion procedure (S2: 56.725 pc/cm^3; Mk5: 56.74 pc/cm^3).

-- VladKondratiev - 28 Mar 2005

%META:FILEATTACHMENT{name="GP_lcp_2084-2100.ps" attr="" comment="" date="1109118833" path="GP_lcp_2084-2100.ps" size="4272" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="GP_lcp_2084-2100.ps" attr="h" comment="" date="1109118833" path="GP_lcp_2084-2100.ps" size="4272" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="pcal.lcp.ps" attr="" comment="Pcal phase pass in LCP" date="1110817862" path="pcal.lcp.ps" size="16669" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="pcal.rcp.ps" attr="" comment="Pcal phase pass in RCP" date="1110817764" path="pcal.rcp.ps" size="16681" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1110582466" path="meander.lcp.X.ps" size="3156304" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1110582507" path="meander.lcp.X.peak.ps" size="18957" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1110582563" path="meander.rcp.Z.ps" size="3171477" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1110582599" path="meander.rcp.Z.peak.ps" size="18941" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="pcal.lcp.ps" attr="" comment="Pcal phase pass in LCP" date="1112028017" path="pcal.lcp.ps" size="18191" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="pcal.rcp.ps" attr="" comment="Pcal phase pass in RCP" date="1112028039" path="pcal.rcp.ps" size="18472" user="VladKondratiev" version="1.3"}% %META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1112029766" path="meander.lcp.X.ps" size="3097858" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1112030307" path="meander.lcp.X.peak.ps" size="18307" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1112029930" path="meander.rcp.Z.ps" size="3103853" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1112030321" path="meander.rcp.Z.peak.ps" size="18317" user="VladKondratiev" version="1.2"}%

%META:FILEATTACHMENT{name="lcp.pcal.ampl.ps" attr="" comment="Pcal amplitude in Mk5 data in LCP" date="1112026040" path="lcp.pcal.ampl.ps" size="18766" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="rcp.pcal.ampl.ps" attr="" comment="Pcal amplitude in Mk5 in RCP" date="1112026068" path="rcp.pcal.ampl.ps" size="19045" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongW.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel W" date="1112026962" path="mk5strongW.ps" size="19034" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongX.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel X" date="1112026992" path="mk5strongX.ps" size="19926" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongY.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Y" date="1112027032" path="mk5strongY.ps" size="19871" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5strongZ.ps" attr="" comment="The strongest GP from 1937 in Mk5, channel Z" date="1112027056" path="mk5strongZ.ps" size="20754" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="lcp.pcal.ampl.zoom.ps" attr="" comment="Pcal harmonic fine structure" date="1112027505" path="lcp.pcal.ampl.zoom.ps" size="32196" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="pcal.phase.ps" attr="" comment="Mk5 & S2 pcal phase curves " date="1112028546" path="pcal.phase.ps" size="19465" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="s2.pcal.ampl.ps" attr="" comment="S2 pcal amplitude" date="1112028732" path="s2.pcal.ampl.ps" size="17338" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_W.ps" attr="" comment="Mk5 Crab GP example, channel W" date="1112031411" path="mk5_crab_W.ps" size="23323" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_X.ps" attr="" comment="Mk5 Crab GP example, channel X" date="1112031437" path="mk5_crab_X.ps" size="23355" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_Y.ps" attr="" comment="Mk5 Crab GP example, channel Y" date="1112031469" path="mk5_crab_Y.ps" size="23125" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="mk5_crab_Z.ps" attr="" comment="Mk5 Crab GP example, channel Z" date="1112031494" path="mk5_crab_Z.ps" size="22645" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="phaseS2WX_1_25.ps" attr="" comment="S2 pcal phase curve" date="1112033379" path="phaseS2WX_1_25.ps" size="12660" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="strongW.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112033791" path="strongW.ps" size="19493" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="strongX.ps" attr="" comment="GP 1937, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112033845" path="strongX.ps" size="21679" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="crab_s2_mk5_W.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2100 - 2116 MHz" date="1112034031" path="crab_s2_mk5_W.ps" size="21152" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="crab_s2_mk5_X.ps" attr="" comment="Crab GP, S2 & Mk5 profiles, 2084 - 2100 MHz" date="1112034069" path="crab_s2_mk5_X.ps" size="21999" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="s2_band.ps" attr="" comment="S2 receiver bandpass" date="1112035371" path="s2_band.ps" size="17258" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="bitstat.tgz" attr="" comment="prg to check & correct for bit statistics of data" date="1112036635" path="bitstat.tgz" size="14972" user="VladKondratiev" version="1.1"}%

The record for S2-RT was "32x4-2", mode "16x8-2" was used for playing our data back from S2 tapes to disk volume.
Description of S2 data format, available modes, user manual, etc. are here.
To decode S2 data program decoder was written. Small description of options can be found by typing "decoder". File "bit.info" should be present which describes the bits placement within data word. This bits placement is determined by used record and playback S2 modes.

-- VladKondratiev - 21 Mar 2005

%META:FILEATTACHMENT{name="decoder.tgz" attr="" comment="program to decode S2 data" date="1111438359" path="decoder.tgz" size="24963" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="s2-doc.tgz" attr="" comment="s2 manual, description of s2 modes, data format" date="1111438567" path="s2-doc.tgz" size="6039430" user="VladKondratiev" version="1.1"}%

-- VladKondratiev - 14 Mar 2005

%META:FILEATTACHMENT{name="pcal.lcp.ps" attr="" comment="Pcal phase pass in LCP" date="1110582308" path="pcal.lcp.ps" size="16444" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="pcal.rcp.ps" attr="" comment="Pcal phase pass in RCP" date="1110582348" path="pcal.rcp.ps" size="16457" user="VladKondratiev" version="1.1"}%

%META:FILEATTACHMENT{name="pcal.lcp.ps" attr="" comment="Pcal phase pass in LCP" date="1110817862" path="pcal.lcp.ps" size="16669" user="VladKondratiev" version="1.2"}% %META:FILEATTACHMENT{name="pcal.rcp.ps" attr="" comment="Pcal phase pass in RCP" date="1110817764" path="pcal.rcp.ps" size="16681" user="VladKondratiev" version="1.2"}%

The phase characteristic curves were built for both polarizations based on Pcal harmonics phase: LCP, RCP. It is seen that phase showes linear pass within the sideband.

During the most part of our observations we had noise-diode turned on. The switching frequency was 80 Hz, so the period is 12.5 ms. With this period we folded the noise-diode meander during of about 15.5 secs (1239 individual meander periods) for all sidebands in each polarization. Here are the examples for LCP-X (2084-2100 MHz) and RCP-Z (2052-2068 MHz). The increasing of system temperature is of about 4.8% (1.2K) for LCP-X and 6% (1.5K) for RCP-Z that is in good agreement with expected values. But very significant peak was found in the rising edge of the noise-diode meander: LCP-X, RCP-Z. The peak temperature is more that twice larger than our system temperature, i.e 122% (55.4K) for LCP-X and 126.4% (56.6K) for RCP-Z with FWHM of about 120 ns.

-- VladKondratiev - 11 Mar 2005

%META:FILEATTACHMENT{name="pcal.lcp.ps" attr="" comment="Pcal phase pass in LCP" date="1110582308" path="pcal.lcp.ps" size="16444" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="pcal.rcp.ps" attr="" comment="Pcal phase pass in RCP" date="1110582348" path="pcal.rcp.ps" size="16457" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.lcp.X.ps" attr="" comment="Noise-diode meander in LCP (2084-2100 MHz)" date="1110582466" path="meander.lcp.X.ps" size="3156304" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.lcp.X.peak.ps" attr="" comment="Noise-diode meander rise edge in LCP-X channel" date="1110582507" path="meander.lcp.X.peak.ps" size="18957" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.rcp.Z.ps" attr="" comment="Noise-diode meander in RCP (2052-2068 MHz)" date="1110582563" path="meander.rcp.Z.ps" size="3171477" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="meander.rcp.Z.peak.ps" attr="" comment="Noise-diode meander rise edge in RCP-Z channel" date="1110582599" path="meander.rcp.Z.peak.ps" size="18941" user="VladKondratiev" version="1.1"}%

Full receiver bandpass form together with interferences in our observations for both circular polarizations: LCP-band.ps, RCP-band.ps. There are based on data from scan2 (duration 50.8375 secs) with frequency resolution of about 15.26 Hz. Number of individual power spectra were averaged is 774.

-- VladKondratiev - 10 Mar 2005

%META:FILEATTACHMENT{name="LCP-band.ps" attr="" comment="Full receiver bandpass in LCP in the observations" date="1110485466" path="LCP-band.ps" size="15903" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="RCP-band.ps" attr="" comment="Full receiver bandpass in RCP in our observations" date="1110485498" path="RCP-band.ps" size="15992" user="VladKondratiev" version="1.1"}%

Crab

Results

-- VladKondratiev - 08 Mar 2005

%META:FILEATTACHMENT{name="p135LCP.ps" attr="" comment="Crab GP profiles in 2-MHz frequency channels (Mk5)" date="1110304438" path="p135LCP.ps" size="43304" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="p135RCP.ps" attr="" comment="Crab GP profiles in 2-MHz freq. chan. in RCP (Mk5)" date="1110304487" path="p135RCP.ps" size="43295" user="VladKondratiev" version="1.1"}%

Decoding data

• All parity bits were removed in our data that is in contrary to info in Mark5 memo #005.2. Parity bits should be removed only in Mark5B system rather than Mark5A which we used.
• All pure data were modulated by a fixed pseudo-random sequence. In memos #230.3 and #230.2 there are only words that data may, optionally, be modulated and nothing about are they usually really modulated, and what is default.
• Barrel-roll was not used. In log information barrel-roll was set to auto-mode, but the header information of sequent data frames shows that there was no changes of track numbers for all bit-streams.
• Digits A11, A12 & A13 were wrong in our data. There was fan-out 1:4 in our data, and these digits were wrong in all of decimated tracks, except the first ones.
• For best results one should use values +3.3359, +1, -1, -3.3359 in the VLBA bit-correspondence scheme as noted in VLBA memo No.5 by L.Kogan. Unfortunately, for now it is not implemented and we used more simple +3, +1, -1, -3 scheme.

For decode our Mark5A data I wrote the program mk5decode. It decodes only the data recorded with mode "512-8-2", i.e pure data rate of 512 Mbit/s for 8 channels using 2-bit sampling. Small description of possible options one can get just typing "mk5decode" or see the code of mk5decode.cpp.

Thanks a lot to Walter Brisken who help me with data format especially with demodulating pure data using pseudo-random modulation pattern.

Results

For the moment scan2, scan3 and 10 min of scan4 were processed. In scan2 we found 5 events above the threshold level of 20sigma, but all of them are false. In scan3 45 events were detected, and only 9 of them can be the true GPs. Number of false events is in good consistency with chi-squared distribution with 2 degrees of freedom.

Average profiles of regular pulses with phases of detected events: scan2 | scan3.
The set of all detected events: scan2 | scan3_true | scan3_false.

-- VladKondratiev - 07 Mar 2005

%META:FILEATTACHMENT{name="mk5decode.tgz" attr="" comment="decoding program" date="1110221918" path="mk5decode.tgz" size="23098" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="scan2_prof.ps" attr="" comment="scan2 average profile of regular pulses" date="1110224422" path="scan2_prof.ps" size="51224" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="scan3_prof.ps" attr="" comment="scan3 average profile of regular pulses" date="1110224446" path="scan3_prof.ps" size="52518" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="scan2_falseGP.ps" attr="" comment="scan2 set of false events" date="1110224473" path="scan2_falseGP.ps" size="106610" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="scan3_trueGP.ps" attr="" comment="scan3 set of true GPs" date="1110224508" path="scan3_trueGP.ps" size="185837" user="VladKondratiev" version="1.1"}% %META:FILEATTACHMENT{name="scan3_falseGP.ps" attr="" comment="scan3 set of false events" date="1110224554" path="scan3_falseGP.ps" size="713634" user="VladKondratiev" version="1.1"}%

Reguest for observations: GBT_VLBI_DAS_test.request

Used configuration

Mark5

• Back-end: VLBI DAS Mark5A
• Band: S
• Observing frequencies: 2100 & 2068 MHz
• Polarizations: LCP & RCP
• Channels: 4 (aka W, X, Y, Z) of 16 MHz each both for RCP and LCP, i.e.
  
  • center freq. 2100 MHz:
    • 2100--2116 MHz, upper sideband (direct spectrum), W
    • 2084--2100 MHz, lower sideband (inverse spectrum), X
  • center freq. 2068 MHz:
    • 2068--2084 MHz, upper sideband (direct spectrum), Y
    • 2052--2068 MHz, lower sideband (inverse spectrum), Z
• Sampling: 2bit

S2

• Back-end: S2
• Band: S
• Observing frequencies: 2100 MHz
• Polarizations: LCP
• Channels: 2 (aka X, W) of 16 MHz each for only LCP, i.e.
  
  • • 2100--2116 MHz, upper sideband (direct spectrum), X
    • 2084--2100 MHz, lower sideband (inverse spectrum), W
• Sampling: 2bit

Supported files

-- VladKondratiev - 04 Mar 2005

%META:FILEATTACHMENT{name="GBT_VLBI_DAS_test.request" attr="" comment="Request description" date="1109952606" path="GBT_VLBI_DAS_test.request" size="1818" user="VladKondratiev" version="1.1"}%

How To Observe with VLBA + Mark5A and VLBA + S2 backends and Reduce Data

How To Observe at the GBT with VLBA + Mark5A and VLBA + S2 backends and Reduce Data

To be filled in with a lot of material.

Test GBT-VLBA-Mark5A / GBT-VLBA-S2 observations

-- YuriKovalev - 18 Feb 2005

VLBI key file (for sched program): GBTtest.key.

Giant pulse from B1937+21 - the first one ever detected using VLBA Mark5A back-end!

Station catalog to be used with the key file. A standard station catalog is corrected in order to support writing to Mark5 disk: stations_test.dat.

• GP_lcp_2084-2100.ps:

As a result of compiling the key file in sched, we get the card file which was used to control the VLBA+Mark5A back-end during the observations: tgbt_05acrd.gb.

-- VladKondratiev - 23 Feb 2005

Test Data Processing

Mark5A data

Giant pulse from B1937+21 - the first one ever detected using VLBA Mark5A back-end: GP_lcp_2084-2100.ps

S2 data

to be presented

-- YuriKovalev - 23 Feb 2005 -- VladKondratiev - 23 Feb 2005

%META:FILEATTACHMENT{name="GBTtest.key" attr="" comment="VLBI key file" date="1109126663" path="GBTtest.key" size="4520" user="YuriKovalev" version="1.1"}% %META:FILEATTACHMENT{name="stations_test.dat" attr="" comment="station catalog with Mark5 disks added" date="1109126825" path="stations_test.dat" size="44370" user="YuriKovalev" version="1.1"}% %META:FILEATTACHMENT{name="tgbt_05acrd.gb" attr="" comment="GBT card file" date="1109126860" path="tgbt_05acrd.gb" size="3477" user="YuriKovalev" version="1.1"}%

Giant pulse from B1937+21 - the first one ever detected using VLBA Mark5A back-end!

• GP_lcp_2084-2100.ps:

-- VladKondratiev - 23 Feb 2005

%META:FILEATTACHMENT{name="GP_lcp_2084-2100.ps" attr="" comment="" date="1109118833" path="GP_lcp_2084-2100.ps" size="4272" user="VladKondratiev" version="1.1"}%

%META:TOPICINFO{author="YuriKovalev" date="1108766799" format="1.0" version="1.1"}%

How To Observe with VLBA + Mark5A and VLBA + S2 backends and Reduce Data

To be filled in with a lot of material.

-- YuriKovalev - 18 Feb 2005