There is a similar set of low cals (that go through a 10 db coupler). The table below shows the receiver name, frequency range of the receiver, frequency where the system temperature is measured, and the cals that are available.high uncorrelated cal with 2 diodes (diode1->polA,diode2->polB) high correlated cal with 1 diode (diode1->polA,diode1->polB) high uncorrelated cal with crossover (diode2->polA,diode1->polB) high correlated cal with 90 deg phase shift (diode2->polA,diode2_90degphase shift->polB)
receiver | freq. range Mhz |
cals | freq. (Mhz) of measurement |
327 | 312-347 | 1 correlated cal | 327 |
430 | 425-435 | all 8 cals | 431 |
800 |
700-800 |
1 correlated cal | 740 |
lbw | 1120-1730 | all 8 cals | 1400 |
alfa |
1220-1520 |
1 correlated |
1375-1520 |
sbw | 1800-3100 | all 8 cals | 2290 |
sbn | 2330-2430 | 1 correlated cal | 2380 |
sbh | 3000-4000 | all 8 cals | 3500 |
cband | 3850-6000 | all 8 cals | 5000 |
xband | 8000-10000 | all 8 cals | 8800 |
line0: Thu Jan 1 16:19:47 2004 az/za lst: 270.0004
10.0000 22:36:05
line1: rcv 5 1400.0 6 3 0 if1 -40.78 -40.17
if2 -54.59 -54.28 cor 0.91 0.94 11 11
line2: 5 hcal 9.550
9.810 27.8 27.2
line 0 columns | line 0 col descriptions |
Thu Jan 1 16:19:47 2004 | date |
270.0004 10.0000 22:36:05 | azimuth, zenith angle, lst when data was taken. |
line 1 columns | line 1 col descriptions |
rcv 5 | receiver numbers: 1-327,2-430,3=610,5-lbw,6-lbn,7-lbw,9-cband,11-xband,12-sbn |
1400.0 | frequency in Mhz where the data was taken |
6 | bandwidth number: 2-25,3-12.5,4-6.25,5-3.125,6-1.5... |
3 | integration time in seconds for cal |
0 | lbw hybrid. 0 out, 1 in |
if1 -40.78 -40.17
|
pwr dbm measured with upstairs power meter. -40 is optimal for lbw,lbn,sbn -32 is optimal for cband,sbw,xband, 430,327 can have less (say -48) since they are narrower bands. |
if2 -54.59 -54.28 | power in dbm from the downstairs power meter. |
cor 0.91 0.94 | correlator 0 lag pola,polB. This is the ratio of
measured to optimum power. If the value is far from 1 then the power levels were wrong (say 20%) |
11 11 | The attenuator values used at the correlator
(polA,polB) The attenutaors go 0 to 15 db |
line 2 columns | line 2 col descriptions |
5 | receiver number |
hcal
|
H is high cal, L is lowCal, D1 is diode 1,D2 is
diode2 H/Lcal: uncorrelated cal (two diodes) D1->pola,D2->polB L/Lxcal: uncorrelated cross over (two diodes) D1->polB,D2->polB H/Lcorcal: correlated cal (one diode). D1->polA,D1->polB H/L90cal: correlate 90deg phaseshift cal. D2->polA,D2+90deg->polB |
9.550 9.810 | Calvalue in kelvins used (polA,polB) |
27.8 27.2 | Tsys computed in kelvins (polA,poB) |
year |
327 302-352 |
430gr 422-442 |
lbw 115-1750 |
sbn 1265-2400 |
sbw 1700-3100 |
sbh 3000-4000 |
cb 4000=6000 |
cbw 4000-8000 |
xb 8000-10000 |
alfa 1220-1520 |
2020 |
327 |
430 |
lbw |
sbn |
sbw |
sbh |
cb |
xb |
alfa |
|
2019 |
327 |
430 |
lbw |
sbn |
sbw |
sbh |
cb |
xb |
alfa |
|
2018 |
327 |
430 |
lbw |
sbn |
sbw |
sbh |
cb |
xb |
alfa |
|
2017 |
327 |
430 |
lbw |
sbn |
sbw |
sbh |
cb |
xb |
alfa |
|
The system temperature is taken daily and then
recorded. If the cals are changed, then it may take awhile for the
new cal values to be measured. So there may be periods of time
when old cal values are being used on new cal diodes. When the new
cal values are installed , you could see a jump in the system
temperature. You should be able to identify these jumps by going
to the cal
values page and looking to see when the new cal values were
installed. Gradual drifts in TsysA-TsysB are probably problems
with the cal diodes drifting.
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