Comparison of analog tv signals and DTV pilot carriers for meteor scatter
116 views
Skip to first unread message
Thomas Ashcraft
May 5, 2015, 12:21:35 PM5/5/15
to sara...@googlegroups.com
http://www.heliotown.com/Meteor_DTV_Pilot_Signal_Test.html
From my location in north central New Mexico: Here is a brief
comparison of meteor scatter received using Mexican analog tv
transmitters and DTV pilot carriers.
The Mexican analog tv transmitters are much more powerful than pilot
signals but meteors are still showing using the DTV pilot signal.
( NOTE: I am lucky to be in proximity to Mexico to receive their analog
tv signals. Most locations in the US may not have the possibilities of
receiving analog tv transmitters so it is worth giving the DTV pilot
carriers a try. )
Thomas Ashcraft Radio Fireball Observatory Heliotown New Mexico
From my location in north central New Mexico: Here is a brief
comparison of meteor scatter received using Mexican analog tv
transmitters and DTV pilot carriers.
The Mexican analog tv transmitters are much more powerful than pilot
signals but meteors are still showing using the DTV pilot signal.
( NOTE: I am lucky to be in proximity to Mexico to receive their analog
tv signals. Most locations in the US may not have the possibilities of
receiving analog tv transmitters so it is worth giving the DTV pilot
carriers a try. )
Thomas Ashcraft Radio Fireball Observatory Heliotown New Mexico
AF7KR
May 18, 2015, 7:39:43 PM5/18/15
to sara...@googlegroups.com
Hi Thomas and group,
I finally have completed a setup that can reliably receive weak signals on 54.310MHz.
The antenna is 3-element Yagi pointed to the direction of the transmitter in Las Vegas, NV. Made of 1/2in PVC pipes and 14ga speaker wire over the weekend.
The distance to the transmitter site is 450km.
I have 2 receivers. The first one is
- simple 2-resonator filter
- LO is 24MHz TCXO + Adafruit Si5351 board + Arduino running NT7S code
- Mixer is SA612A, demodulating in DSB mode
- 100x audio amplifier using LM358 opamp
- Acer 1005HA netbook running Mint 17 and Spectrum Lab under Wine. Sound input is left channel only, no I/Q in this system.
The second receiver is a similar 2-resonator filter + ThumbNet RTL-SDR dongle:
http://www.rtl-sdr.com/thumbnet-special-rtl-sdr-tcxo-type-f-connector-r820t2/
Same netbook running rtl_fm, SSB demodulated output piped to SpectrumLab.
Both receivers show very good frequency stability and good enough sensitivity (noise level increases by about 6-10dB when antenna is connected).
A "regular" RTL-SDR dongle drifts by 200Hz over 3-5C temp change in my shack. ThumbNet dongle stays within few Hz.
I see good numbers of pings, but results are not that great because of the plane reflections. The distance is small enough to see LOTS of them. One at a time would not be a problem, but during the day there are typically 2-3-4 at a time. Crossing traces are a real challenge for the Spectrum Lab counting algorithm. I need to work on morphology based image processing algorithms to count pings reliably in this kind of data.
Not that much time left before the digital switchover in Mexico :(
73, Mike AF7KR
I finally have completed a setup that can reliably receive weak signals on 54.310MHz.
The antenna is 3-element Yagi pointed to the direction of the transmitter in Las Vegas, NV. Made of 1/2in PVC pipes and 14ga speaker wire over the weekend.
The distance to the transmitter site is 450km.
I have 2 receivers. The first one is
- simple 2-resonator filter
- LO is 24MHz TCXO + Adafruit Si5351 board + Arduino running NT7S code
- Mixer is SA612A, demodulating in DSB mode
- 100x audio amplifier using LM358 opamp
- Acer 1005HA netbook running Mint 17 and Spectrum Lab under Wine. Sound input is left channel only, no I/Q in this system.
The second receiver is a similar 2-resonator filter + ThumbNet RTL-SDR dongle:
http://www.rtl-sdr.com/thumbnet-special-rtl-sdr-tcxo-type-f-connector-r820t2/
Same netbook running rtl_fm, SSB demodulated output piped to SpectrumLab.
Both receivers show very good frequency stability and good enough sensitivity (noise level increases by about 6-10dB when antenna is connected).
A "regular" RTL-SDR dongle drifts by 200Hz over 3-5C temp change in my shack. ThumbNet dongle stays within few Hz.
I see good numbers of pings, but results are not that great because of the plane reflections. The distance is small enough to see LOTS of them. One at a time would not be a problem, but during the day there are typically 2-3-4 at a time. Crossing traces are a real challenge for the Spectrum Lab counting algorithm. I need to work on morphology based image processing algorithms to count pings reliably in this kind of data.
Not that much time left before the digital switchover in Mexico :(
73, Mike AF7KR
0 new messages