3mm primary focus receiver (84000-95500 MHz)

This is a 3-channel dual-feed system designed for VLBI observations. Since some years there exists a NASA satellite that operates a radar at 90 GHz. The radar is called CloudSat and is powerful enough too not only produce RFI, but it can also destroy the receiver when passing inside the beam. Please check the CloudSat homepage when planning 3mm observations. The CloudSat page also provides a forecast for satellite passages at specific radio observatories: here for Effelsberg.

Calibration Information

Frequency [GHz] Channel Polarisation Tcal [K] Tsys [K] Sensitivity [K/Jy] SEFD [Jy] Aperture Eff. [%] TMB/S [K/Jy] Main Beam Eff. [%] FWHM [arcsec] Last update
86.25 A LCP 13.1 158 0.14 1154 4.8 1.38 10 10.9 Mar 2013
86.25 B RCP 16.7 161 0.14 1174 4.8 1.37 10 10.9 Mar 2013
normalized Gain curve (G = A0 + A1·Elv + A2·Elv2) Observed in confirmed
A0= 0.63495A1=2.3001E-2 A2=-3.6231E-4May 2012

Comments:

  • Tcal for channel C, the weather horn, is about 42 K, Tsys about 150K.
  • The calibration parameters for this receiver strongly depend on the weather conditions.

Version description for OBSINP

RX Name Wavelength [cm] Frequency (center) [GHz] Nr. of Horns
P3mm 4-Box (84-87 GHz) 0.3 84.0-95.5 1
Version: Comment
1. Cont./Line/VLBI (BW: 500 MHz) Continuum, spectroscopy, and VLBI version
2. Pulsar (BW: 500 MHz) Pulsar version
Horn offsets [arcsec] -1070.5, 1046.6

Channel assignment in the MBFITS data files

Note that the narrow line and VLBA IF channels are usually only available when the specific line version of the receiver was selected. In addition for most receivers with narrow line channels the cables at the patch board need to be connected by the receiver group.

To select different channel numbers in OBSINP, the online plot, or the toolbox the numbers have to be specified like c(1)+c(2) to add channel 1 and 2. E.g. channel 1 and 2 contain the LCP and RCP broadband channels, then "OnlPlot pen='c(1)+c(2)'" or "toolbox use='c(1)+c(2)'" will select these channels. In OBSINP the pen can be directly specified in the receiver selection menu.

Abbreviations:
SB: narrow band channel (Schmalband-Kanal), 100 MHz band width
BB: digital broad band channel (Breitband-Kanal), band width varies for different receivers
VLBA: VLBA IF, 500 MHz band width
BW: band width
TP: total power

3mm PFK (Multi-RX-Box II)
Channel IF Pol. Comment
1 BB LCP Horn 1, TP A
2 BB RCP Horn 1, TP B
3 BB RCP Horn 2, TP A
4 VLBA LCP TP A
5 VLBA RCP TP B
6 VLBA cross cos AB
7 VLBA cross sin AB

Spectroscopy modes and resolution

BW nchan nu Df Dv dv
MHz MHz kHz km/s km/s
100 32768 85000 3.1 0.011 0.012
100 32768 87000 3.1 0.011 0.012
100 32768 89000 3.1 0.010 0.012
100 32768 91000 3.1 0.010 0.012
100 32768 93000 3.1 0.010 0.011
100 32768 95000 3.1 0.010 0.011
500 32768 85000 15.3 0.054 0.062
500 32768 87000 15.3 0.053 0.061
500 32768 89000 15.3 0.051 0.060
500 32768 91000 15.3 0.050 0.058
500 32768 93000 15.3 0.049 0.057
500 32768 95000 15.3 0.048 0.056

BW … band width
nchan … number of spectral channels
nu … center frequency
Df … Channel separation (in frequency)
Dv … Channel separation (in velocity)
dv … Velocity resolution (dv=1.16*Dv)

Tcal and Tsys measurements

 
information_for_astronomers/rx/p3mm.txt · Last modified: 2017/10/12 14:30 by ubach     Back to top