[amsat-bb] SatPC32 leading the satellite

Jim White jim at coloradosatellite.com
Fri Jul 1 13:03:35 UTC 2016


Thanks Erich,
Jim

On 7/1/2016 12:28 AM, Erich Eichmann wrote:
> There are the following options in menu "Rotor Setup" they could have 
> used to update the azimuth and elevation antenna positions:
> a. in time increments, say 3 seconds or less.
> b. when the satellite's position (azimuth or elevation) changed by a 
> certain CONSTANT amount of degrees (dead band), say 3 degrees (their 
> setting) or less.
> The program then updates both antennas every 3 seconds or whenever the 
> azimuth or elevation changed by fix 3 or more degrees. Then It  
> positons the antennas  a half step in front of the current satellite 
> position. So, the satellite will run through the "focus" of the antenna.
>
> There is a sub option of b. (which they used):  "gain releated". When 
> the elevation increases the azimuth position of the satellite changes 
> very quickly and the azimuth antenna positon will be updated very 
> often.  On the other hand the  horizontal opening angle of the antenna 
> becomes virtually wider,  following a cosine function (at 90 degs 
> elevation  azimuth is meaningless). The feature utilizes this effect 
> to reduce the number of horizontal updates without loss of gain. Also, 
> the signal is stronger at high elevation angles, due to the smaller 
> distance of the satellite. So,  with a small update step they should 
> not loose data,  even with the setting "gain related".
> That all is  described in the manual (menus "Rotor" and "Rotor Setup").
>
> 73s, Erich, DK1TB
>
>
>
> Am 01.07.2016 um 03:55 schrieb Jim White:
>> I was at a university ground station today and noted their antennas 
>> were not keeping up with their satellite on a high elevation pass. 
>> They are using SatPC32 with the G5500 rotor.  They have the dead band 
>> set to 3 degrees. Since they are using a pair of long UHF Yagis for a 
>> total of 21dB gain there were some lost packets for about 2 minutes 
>> or so around TCA.  Their sat was deployed from the ISS so is 
>> currently at about 400km altitude which means it's zipping by rather 
>> quickly when the elevation is above about 75 degrees or so.
>>
>> In the past I've used tracking programs that allowed a 'lead' 
>> setting.  That is, you could tell the software to lead the satellite 
>> by a few seconds. That did a pretty good job keeping the sat in the 
>> beam width when the AZ was changing quickly. I'm not finding that 
>> setting in SatPC32.  Is there one, or another setting to accomplish 
>> the same thing?
>>
>> Jim
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