[amsat-bb] Re: finding yourself in the passband of an analog satellite

na2x@yahoo.com na2x at yahoo.com
Thu Jan 20 11:13:03 PST 2011

Hi Norm,

Good question.  It brings to mind another question (a second post coming).

To do it manually, I first start with the info for the satellite found at:

For example, under VO-52, it shows (for the Indian Transponder)

Mode U/V (B) Linear Transponder (Inverting) (Indian Transponder): Operational
Uplink:        435.2200 - 435.2800 MHz SSB/CW
Downlink       145.9300 - 145.8700 MHz SSB/CW

I read this to mean that (with no doppler) for this transponder, an uplink input frequency of 435.2200 MHz  will result in a downlink frequency of 145.9300 MHz, etc., etc.

I make up a small table for each satellite showing uplink and downlink frequencies across the range of frequencies.  So for VO-52 (Indian Transponder), the table looks like this:

Uplink          Downlink
435.22 MHz      145.87 MHz
435.23 MHz      145.88 MHz
435.24 MHz      145.89 MHz
435.25 MHz      145.90 MHz
435.26 MHz      145.91 MHz
435.27 MHz      145.92 MHz
435.28 MHz      145.93 MHz

Of course, you can put as many entries in the table as you wish. You could have every Khz frequency in the range. I use this information as a starting point.  Doppler will move the downlink receive frequency.

So, for this satellite, if I hear some one calling CQ on 145.890 Mhz, I know I should start at an uplink frequency of around 435.240 Mhz and then tune around to find my downlink to match other station.


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