Satgen67    Uosat3 9600 bps FSK - Simple Operating Notes   10th July 90

Have been trying to develope my tracking and copying abilities on Uosat3
UO-14, using very simple hardware which occupies a tiny space on my
operating bench. The equipment consists of an Az El trainable 48 element
70cm multibeam, feeding a Microwave Modules UHF/HF converter modified for
Mod 1.  435.07 to 27.67 MHz conversion , Mod 2. 10KHz inter channel tuning
via a 5/60pF variable capacitor in series with the converter L osc xtal
(5th overtone 101.85MHz ). The converter feeds a UK 27.61 to 27.99MHz FM
CB, Mod 3. wired for Rx only, which is fitted ,Mod 4.  with a replacement,
wideband 12KHz 2nd IF ceramic filter and,Mod 5.  Rx audio output from pin
9 of IC MC3357 FM discriminator. This Rx audio goes to a home built G3RUH
9600 modem and thence to a modified TNC 320 and then to an IBM PC. To use
it I get a computer prediction print out Table 1.
Table 1 Uosat 3 Oscar 14 on 8/7/90
 UTC   AZ    EL    Lat  Long  SigFreq + Doppler KHz
1949   103    0     41   325    435078.8       = AOS
1950    99    2     45   327    435078.5
1951    93    5     48   328    435078.1
1952    86    9     52   330    435077.2

I set the antenna pointing at AOS Az 103 and El 0, then  check my tuning
calibration Table 2 and set the CB channel to  9 and the converter inter
channel tuning vcap to 68, ready for a signal on 435078.8

Table 2  Channel and Inter channel calibration versus Frequency
FreqKHz CBCh Vcap  FreqKhz CBCh Vcap  FreqKHz CBCh Vcap FreqKHz CBCh Vcap
435080    9   80 : 435075    9   30 : 435070    8   80 : 435065    8   30
435079    9   70 : 435074    9   20 : 435069    8   70 : 435064    8   20
435078    9   60 : 435073    9   10 : 435068    8   60 : 435063    8   10
435077    9   50 : 435072    9    0 : 435067    8   50 : 435062    7  100
435076    9   40 : 435071    8   90 : 435066    8   40 : 435061    7   90

The system runs in by itself at AOS and starts to produce screen copy. I
monitor the signal "eye diagram" on the scope. Tune up if the bottom of
the eyes flatten out. Tune down if the top of the eyes start to lean
over.Good tuning being indicated by perfect diamond shaped "eyes". Good
tracking being shown by clear "eyes" , not blurred by noise.
When on tune, I note channel and inter channel settings and read across
Table 2 to get the frequency Eg 9 61 = 435078.1KHz , which read across to
Table 1 shows I need to retrain my antenna to Az 93 El 5. My Keplerian
elements need not be perfectly accurate for time , but I can get good
tracking despite this, and use a relatively high gain antenna. 
A cheap but effective way to get results! Has anyone tried a similar
approach to Pacsat BPSK reception. Let me know if you have. 73 de John
GM4IHJ @ GB7MAC 10th July 90