I am using SDR#
How common is 8.33 kHz channel spacing on the US?
- Thread starter KC0QNB
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Is that one of the studio versions? Still looking in cell phone.
Yep
AIRSPY SDR# STUDIO v 1.0.0.1921 32 bit
AIRSPY SDR# STUDIO v 1.0.0.1921 32 bit
In that case I'm perplexed. Perhaps some locally generated interference within your system? Try putting your cursor over the 100KHz digit of the frequency display at the top of the screen and observe any changes as you scroll up and down in 100 KHz steps with the mouse wheel during a transmission. Then try 1 KHz steps.
Another test would be to shift the receive frequency away from the center of the display and see if that makes a difference. Also try unchecking "Correct IQ" just for the heck of it.
Do you notice any change in sound between 8.333 & 25 KHz steps with the squelch open and no transmission?
Just looking for clues.
Most of these frequencies are only active for a few seconds at a time, I can try it though. I can also try the open squelch thing though. When I searched online about how to check the ppm I read I could tune to a weather radio frequency, which is NFM.
Wx radio does not use NBFM; they use a 25KHz wide channel.
There is no discernable difference in the sound between 25 and 8.33 kHz channel spacing. I did tune a WX radio nearby at 162.425 mHz it was right on.
I tuned one nearby and by golly NFM in this case is a 25 khz wide channel, however NBFM and NFM are often used interchangeably. At any rate the 160.425 mHz WX radio signal is spot on
For my next experiment concerning whether or not the ppm is correct I will change to my HF antenna and confirm with WWV.
spanky15805
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Ryan, don't know much about railroad weather on 160.425. Are you talking about hotbox detectors and axle count?
Oops I meant 162.425. But now that you mention it I live less than a mile from the UPRR triple track main here they operate on a road frequency 160.470, and I hear a defect detector several times a day. Been that way for years, not sure why they haven't fixed it.
G7RUX
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Was it a set of ground transmitters using offset frequencies?
When I scan a know freq at 12.5, 6.25 or 25, it parks right there and signal appears within the bandwidth of 10,000 and usually dead on.
When I select same freq with 8.33, it shifts up to 118.177 which is 2 khz higher, not dead on, and it comes in fuzzy and unintelligible. .
What antenna are you using and how far away are these planes your hearing? Asking because I see your gain is maxed out.
When I select same freq with 8.33, it shifts up to 118.177 which is 2 khz higher, not dead on, and it comes in fuzzy and unintelligible. .
What antenna are you using and how far away are these planes your hearing? Asking because I see your gain is maxed out.
I am using an old Cushcraft Ringo, 2-meter antenna, my RS discone is 200 miles away, if it is still in one piece. I do not need the RF gain that high, it just ended up that way. As far as how far the planes are away, depending on their altitude they could be 200-300 miles away.
I found a site that tries to explain the 25 kHz and 8.33 kHz relationship, it makes more sense now.
VHF airband - HFUnderground
I am using an old Cushcraft Ringo, 2-meter antenna, my RS discone is 200 miles away, if it is still in one piece. I do not need the RF gain that high, it just ended up that way. As far as how far the planes are away, depending on their altitude they could be 200-300 miles away.
I found a site that tries to explain the 25 kHz and 8.33 kHz relationship, it makes more sense now.
VHF airband - HFUnderground
www.hfunderground.com
Planes are tricky cause if you zoom your spectrum in you will see many air radios are not dead on. I have one instance of sdr# just for airband because I played with many of the filter settings to get audio to my liking.
Noticed studio does not have snap to grid where the older 17xx versions do.
Noticed studio does not have snap to grid where the older 17xx versions do.
OK time to put the discussion with my Dongle PPM being wrong to rest I tuned to WWV a few minutes after changing to my HF antenna. this is a screenshot of that experiment.
When you can, with same settings, try one of the 162.xxx weather freqs (157 mhz higher )and see what you get. Then look for a control channel in 7/8/900 mhz and see what you get. I noticed my dongles require ppm adjustment between lower and higher freqs. If I tune to weather or even low band, and set it, and then go to 7/8/900, it needs to be adjusted.
Here you go...
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