Links

Testing the QRFH with on the telescope with a warm rcvr system.
commissioning the cooled rcvr on the telescope.
    shimming the horn to find the focus
computed rcvr chain levels
Measured power levels



Doc:
Arecibo_cryofrontEnd documentation Ver1 3dec22 (.pdf)
Labjack documentation
Edwards WRG vacuum gauge manual (.pdf)
papers
hamdi's updates

---

intro

    Hamdi mani is building a cooled wideband receiver for the 12meter telescope. It will use the QRFH (QuadRidgeFlaredHorn).

---

Computed receiver chain levels.

The parameters for the components in the wideband receiver chain were used to compute the levels as you move through the chain.
I've computed this for 2 different setups:

• xband cables down to the pedestal with 1.7 db insertion loss for the filters
  
• xband cables down to the pedestal with 15db insertion loss for the straight thru mode
  
• we swithed the straight thru cable to a 15db pad to try and  cut down the saturation in this filter selection.
  

• The program sysTemp (/share/megs/phil/svn/aosoft/src/gen/srcTemp.c) was used for the computation.
• If you want to play around with the parameters:
• /share/megs/phil/svn/aosoft/p12m/rcvtemp/wbrcv/  has a few scripts run the different configs
•  (rcvtemp.sc)
  
• You can copy,edit the xxx.dat files to play with things.
  
• If you want to write the output to a file, then use a directory you have write permissions to.
• sysTemp should be in your path by default. If not use:/pkg/aosoft/fedora4/x86_64/bin/sysTemp
  
• wbrcv_xbcbl.tmpl - template for xband cable setup with 1.7 db filter insertion loss
• wbrcv_xbcblstr.tmpl - template for xband cable setup with 15db pad for filter insertion loss (instead of a short cable)
  
• Contains configured elements. For some elements a shell variable is used so it can be modified for different frequencies
• For the values with no freq dependence, they are hard coded here (eg tscattered)
  
• wbrcvdrv_xbcbl.sc shell script for xband cable setup
  
• defines the shell variables that appear in wbrcv_xbclb.tmpl.tmpl,wbrcv_xbcblstr.tmpl. It has values for 3,5,8,12 GHz
• for each of the 4 frequencies
• defines the shell variables
• inputs wbrcv_xbcbl.tmpl or wbrcv_xbcblstr.templ
  
• loads the shell variables with the defined values
• outputs an ascii file to wbrcvFreq_xbcbl.dat or wbrcvFreq_xbcblstr.dat (where Freq is 3,5,8,12) ghz
• runs rcvtemp.sc on each of these wbrcvN.dat files creating
• systemp_wbrcvN_xbcbl.out or systemp_wbrcvN_xbcblstr.out . they contain the values for a particular freqN
• if you wanted to  play with a single file:
• copy one of the wbrcvN_xxx.dat files .. wbrcvTest.dat
  
• edit it for whatever you want
• then run
• rcvtemp.sc wbrcvTest
• this will generate systemp_wbrcvTest.out
• the rcvr chain names are:
• sky temp degK
• Taken from paul goldsmiths tsky plot (dry air, za=0)
• tscat : temp scattered radiation degK
  
• i've hardcoded it to 10
• lna : low noise amplifier tenp degK and gain: db
  
• used trcv measured at the test range. Had to use hamdi's lab measurements for freq with lots of rfi.
• cLnaToFb: cable dewar to filterbank box
• fbAmp1: filter bank amp at input. degK and gaindb
• fbLpfilt:  filter bank low pass filter before the switchable filters. 0 to 14Ghz
  
• fb1to8_in: input switch selector (6 port)
• fbfilt_sel:  insertion loss for filter selected
  
• hardcoded to -1.7db gain for all filters
• set to 15db for straight thru mode (separate set with xbcblstr.xxx ..
  
• fb8to1_out: 8 to 1 switch on filter bank output
• cFbtoHub: cable filter bank to hub. (used 25' cable loss )
• gHubAmp:  gain for hub amp (from datasheet)
  
• nfHubAmp  noise figure for hub amp (from datasheet)
  
• cHubtoPed: cable hub amp to pedestal. I made the cumulative cable loss equal to the measured sband cable loss.
  
• pedAmp:    pedestal amp (at input to fiber box)
• pedattn1:    3db pad after amp
• pedcplr     :   10db coupler before fiber optic xmiter (less us measure power into foTx ..)
• pedattn2    : 12db pad after coupler before foTx.. added  25may23
  
• fotxrx    :    fiber optic tx,rx.. noise fibure and gain.
• The output
• col1 element name
• col2 noise figure for the element in db
• col3 Temp for this element in degK
• col4 gain   of object in db
• col5 cumulative gain of the rcvr chain at the input to this element
  
• col6 temperature at input to this element degK
• col7 Tsys contribution for this element
• The bottom of the page:
• temp At output of last element
• Tsys
• cumulative gain
• Note:
• the CumGain,tempInp are at the input to the element. To get the output after the last element you have to look at the values at the bottom.

freq	xbcables	xbcable, straightThruFilterMode,15db pad
3Ghz	systemp:_wbrcv3_xbcbl.txt	systemp_wbrcv3_xbcblstr.txt
5Ghz	systemp_wbrcv5_xbcbl.txt	systemp_wbrcv5_xbcblstr.txt
8Ghz	systemp_wbrcv8_xbcblstr.txt	systemp_wbrcv8_xbcblstr.txt
12Ghz	systemp_wbrcv12_xbcbl.txt	systemp_wbrcv12_xbcblstr.txt

History:

• 17apr23: updated fb to pedestal cable loss using 13apr23 s2p measurements. need to get better s/n for higher freq.
• 26apr23:
  
• updated insertion loss of 0-14 ghz lowpass filter in filter box  2db -> .25 db
• added temps using xband cables and hub amps
• cable loss are estimates.
• 27apr23:
  
• pedestal amp before fo tx. updated values to those in the datasheet.
• 18may23:
• updated cable dewar to filterbox to correct values
• updated fiberopitc box to correct values
• now values always use xband cables
• found compression in straight thru mode so:
• switched filter bank straight thru cable to a 15 db pad to try and cut down on compression
• ok at lower freq but adds about 30K at 12Ghz (where you don't need to use straight thru mode)
• 29may23:
• 12db pad in front of foTx out. straight thru will not saturate foTx 
• 30may23:
• added 20db solar attenuator to computations since fb 3,5 need it in.  filter 6 (xb) doesn't use it.
  

Notes:

•  some of the are probably a bit off
• sky temp.. probably low .. especially  if clouds and lower elevations
• Tscatter: just a guestimate.
  

processing: aosoft/p12m/rcvtemp/wbrcv/wbrcvdrv.sc

---

measured power levels

at fiber optic coupler
At udc input
power levels that work

At fiber optic coupler:

• There is a 10db coupler in front of the FoTx.
  
• measurements are done on it and then 10db is added to get to the FoTx input value
• dates that affected power power measurements
• 18may23: straight thru mode is a cable
• 25may23: straight thru mode is a 15 db pad
• 16:00 12db pad put after the coupler and before the FoTx input.
• udc input measurements, and cal stepping done after this was installed
• Values quotes are those measured at the coupler, and then those at the FoTx input
• The fiber optic 1db compression is 10 dbm
• For no compression you should  be around 0dbm.
  
• The 1db compression of the amp before FoTx is about 25dbm output
• there is a 3db pad between the amp and the coupler input, so a 22db input at the foTx will have the amp in saturation.
  
• * -> foTx will saturate
• **-> foTx and probably amp before coupler will saturate
• data: (PolA,PolB)
• Current values
  
• 
  

• Date/location		straight thru fb:1	2940-4240 fb:2	2775-3475 fb:3	3180-3340 fb :4	4600-14000 fb:5	8050-9200 fb:6	Notes
  18may23: straight thru is cable, not pad
  on sky	at cplr	(13,11)	(4,4)	(-19.9,-21.3)	(-27.9,-29.6)	(-24.2,-25.)	(-37.62,-36.8)	Az=-95,el=5.9
  	at FoTx	(23,21)**	(14,14)*	(-9.9,-11.3)	(-17.9,-19.6)	(-14.2,-15)	(-27.6,-26.8)
  On Abs	at cplr	(4,6)	(-3,-2)	(-13,-15)	(-21.6,-23)	(-18,-19)	(-32,-32)
  	at FoTx	(14,16)*	(7,8)	(-3,-5)	(-11.6,-13)	(-8,-9)	-(12,-12)
  On Sun	at cplr	(13,)	(9,,-)	(-4.5,)	(-4.5,)	(-3.9,)	(-20.4,)	polb not measured
  	at FoTx	(23,)**	(19,-)	(5.5,)	(5.5.,)	(6.1)	(-10.4)
  25may23: straight thru=15db pad, no 12db pad in front of  foTx 29may23: removed 12db in front of foTx again
  on sky	at cplr	(0,-1.3)	(3.2,3)	(-16,-18.7)	(-25.0,-26.9)	(-20.9,-22.4)	(-33.5,-34.1)	az=90,el=6
  	at FoTx	(10,8.7)*	(13,12.3)*	(-6,-8.7)	(-15.0,-16.9)	(-10.9,-12.4)	(-23.5,-24.1)
  on sky	at cplr	(0,-2)	(6,6)	(-17.9,-19.7)	(-26.2,-27.8)	(-22.8,-24.1)	(-37.2,-37.)	az=90,el=70
  	at FoTx	(10,8)*	(16,16)*	(-7.9,-9.7)	(-16.2,-17.8)	(-12.8,-14.1)	(-27.2,-27.)
  On sun	at cplr	(3,-.6)	(9.9,8.4)	(5.4,3.35)	(-3.5,-5.46)	(-3.3,-4.3)	(-19.7,-19)	az=-80,el=65
  	at FoTx	(13,9.4)*	(19.9,18.4)*	(15.4,13.35)*	(6.5,4.54)	(6.7,5.7)	(-9.7,-9)
  25may23: 12db pad added after coupler, before FoTx. Computed FoTx output from previous measurements
  on sky	at FoTx	(-2,-3.3)	(1,.3)	(-18,-20.7)	(-27,-28.9)	(-22.9,-24.4)	(-35.5,-36.1)	az=90,el=6
  on sky	at FoTx	(-2,-4)	(4,4)	(-19.9,-21.7)	(-28.2,-29.8)	(-24.8,-26.1)	(-39.2,-39.0)	az=90,el=70
  on sun	at FoTx	(1,-2.6)	(7.9,6.4)	(3.4,1.35)	(-5.5,-7.46)	(-5.3,-6.3)	(-21.7,-21)	az=-80,el=65

•  
• 230518:
• straight thru mode is a cable.
  
• straight thru mode in the filterbank passed 2.5 to14 ghz (with no attenuation)
  
• it was always compressing the FoTx
• The measured value on sky and on the sun were the sun (so we were well into compression)
• We still saw strong rfi when on absorber (The other pol was plugged into the field fox spectrum analyzer.)
• straight thru mode and the 2940-4240 filter always showed unstable bandpasses
• the 2940-4240 bandpass filter does not fall off very fast so it was always seeing the strong rfi 2500-2700 Mhz.
• 230518
• added 15 db pad for straight thru mode
• added 12db pad before FoTx.

At UDC input

• The power meter was used to measure the power  after the fiber optic receiver in the wapp room.
• The udc compression:
•  -35 dbm input.  1db compression
• -45 to -35dbm  some compression
  
• 
  
• all numbers are in dbm.67
• *-> udc will be at least 1db compressed
• SolAttn is the 20db attenuator before the udc. 1 -> in, 0 -> no in
  

date	straight thru fb:1	2940-4240 fb:2	2775-3475 fb:3	3180-3340 fb :4	4600-14000 fb:5	8050-9200 fb:6	Notes
25may23: 12db pad in front of fotx. on sky
solAttn=0	(-30,)*	(-27,)*	(-46,)	(-53,)	(-52,)	(-67,)	az=10,el=45
29may23 12db pad out, on sky
solAttn=0	(-20,-16.3)*	(-19.9,-14.2)*	(-38.3,-36.2)	(-46.5,-43.8)	-41.8,-39.7)	(-55.6,-50.6)	az=44,el=60
solAttn=1	(-35,-36.8)*	( -, -34.8)*	-53.5,-56.5)	(-,-67.5)	(-57.6,-60.7)	--

• 25may18:
• only polA measured, 12db pad in front of FOTx installed
• -67dbm is probably the noise floor of the power meter.
• 
  

Fiber optic loss

• using the power levels measured at the FoTx input and the FoRcv output we can get estimate for the loss in the fiber optic system.
• 220317 felix measured the fiber optic system 0 to 4 Ghz.
  
• short cable tx to rx gain -16db, NF 24db
• ctrlRoom to 12m  : gain:-21db, NF 28db
• 230525: looking at the power meter at foTx input and foRcv output
  
• not done at same az,el or same time so things could change.
• fotxInp=-2dbm, foRxOut= -30db..gain: -28 db
• This used the straight thru mode with 15db pad and 12db pad
• the power at the higher freq may be close to the noise floor of the fo system.
  

What configurations will work/not work

key:

• SatFo  - fiber optics not 10db below 1db compression
• SatUdc- udc input not 10db below 1db compression.
  

Config	straight Thru fb:1	2940-4240 fb:2	2775-4240 fb:3	3180-3340 fb :4	4600-14000 fb:5	8050-9200 fb:6
Sky
no 15db pad no 12db pad	satFo,satUdc	satFo,satUdc	-	-	-	-
15db pad	satFo,satUdc	satFo,satUdc	-	-	-	-
12db pad	-	satFo,satUdc	-	-	-	-
Sun
no 15db pad no 12db pad	satFo,satUdc	satFo,satUdc	satFo,satUdc	satFo,satUdc	satFo,satUdc	-
15db pad	satFo,satUdc	satFo,satUdc	satFo,satUdc	satFo,satUdc	satFo,satUdc
12db pad	satFo,satUdc	satFo,satUdc	satFo,satUdc	-	-	-

---

hamdi's updates

• 220410 - gain,s11 2 candidate lna's,qrfh response with lna's (simulation). some commercial filters (simulation). (.pdf)
• 220530 - qrfh feed assembled. start testing.
  
• 220530 - first measurement of return loss and cross coupling (.pdf)
• still needs some tuning.
• 220531: 2.5 Ghz hipass filter response. warm and cold (libreoffice.calc)
  
• 220603 : better tuning of qrfh feed. s11 improves
• room temp lna for tests, the rfi filters.
• 220617: Tsys from warm receiver measurements.