campag5242
Feed Hunter
- Messages
- 2,585
Lyngsat & kingofsat both seem to list feed TPs verbatim using details reported by users, & without trying to correct for measurement errors in reported user data. Same goes with this site. Nor can I find "official" lists of feed transponders.
The most common variable is frequency - this is made up of a systematic error ie an LNB's local oscillator centre-frequency (LOF offset) / set-top-box's LOF drift (both temperature-dependant), plus random sampling error. I assume a multi-million $ satellite's electronics are temperature & (special & general) relativity compensated, so as to emit rock-solid frequencies.
Enhancing https://www.sat-universe.com/showthread.php?t=309092 to auto-calibrate LOF offset & show frequencies to a resolution of 10 kHz, I am starting to see patterns: frequencies might be be aligned to 250kHz boundaries. (I have a physics background so am a stickler for such things).
Helpful in making sense of what might appear to be random feed frequencies is the spectral bandwith which a feed uses for given SR: bandwidth in MHz ~= 1.2 * SR in ksps. This determines the spacing of tightly-packed, adjacent feed TPs eg the commonly use SR around 7200ksps are spaced by 9MHz, 9875 by 12MHz, 14400 by 18MHz etc.
My best estimate for the first 72MHz of spectrum allocated to feeds on 7E, 10955.5-11027.5MHz (both H&V), follows in the next post.
The most common variable is frequency - this is made up of a systematic error ie an LNB's local oscillator centre-frequency (LOF offset) / set-top-box's LOF drift (both temperature-dependant), plus random sampling error. I assume a multi-million $ satellite's electronics are temperature & (special & general) relativity compensated, so as to emit rock-solid frequencies.
Enhancing https://www.sat-universe.com/showthread.php?t=309092 to auto-calibrate LOF offset & show frequencies to a resolution of 10 kHz, I am starting to see patterns: frequencies might be be aligned to 250kHz boundaries. (I have a physics background so am a stickler for such things).
Helpful in making sense of what might appear to be random feed frequencies is the spectral bandwith which a feed uses for given SR: bandwidth in MHz ~= 1.2 * SR in ksps. This determines the spacing of tightly-packed, adjacent feed TPs eg the commonly use SR around 7200ksps are spaced by 9MHz, 9875 by 12MHz, 14400 by 18MHz etc.
My best estimate for the first 72MHz of spectrum allocated to feeds on 7E, 10955.5-11027.5MHz (both H&V), follows in the next post.
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