4 ms·

Not sure your exact use-case but if you are frequency-limited by the RTL and you feel like soldering, you can mod a SUP-2400[0] to be a 4.5GHz downconverter for

by scrps 5y ago

Not sure your exact use-case but if you are frequency-limited by the RTL and you feel like soldering, you can mod a SUP-2400[0] to be a 4.5GHz downconverter for the RTL[1]. [0]: https://www.solidsignal.com/zinwell-directv-b-band-converter-module-sup-2400 https://www.solidsignal.com/zinwell-directv-b-band-converter... [1]: https://www.kd0cq.com/2016/04/part-ii-the-mod-receive-up-to-4-5ghz-on-your-rtlsdr-for-5-00/ https://www.kd0cq.com/2016/04/part-ii-the-mod-receive-up-to-...

tzs 5y ago
The last project for which I was considering a LimeSDR the problem with my RTL-SDR was bandwidth. Last summer I made a TV antenna and tried to find a good location for it outdoors. There were two difficulties. 1. My Samsung TV has a lousy interface for setting up an antenna. It will only let you view signal strength on known channels. By "known" I mean a channel that it found when you told it to scan for channels, or a channel that you manually tuned to and it found a sufficiently strong signal. A scan for channels starts off by forgetting all known channels. The channels here come from two different directions. This meant there was a lot of setting up the antenna and pointing it toward one group of channels, going back in the house and doing a scan, noting the signal strength for all the known channel, then going back out and turning the antenna toward the other group, coming back in and seeing what channels I still had good signal on from the known channels, and then manually tuning to the channels in the second group to see if I could get any of them well enough for them to become known. After that, there was then going back out, and systematically trying different antenna aiming to find some direction that gets me the best compromise between the two directional groups. When viewing the signal strength display, you can only change channels with channel up/channel down, which steps through all the sub-channels. The stupid Samsung interface has almost no command buffering, so suppose channels 13, 16, 20, and 22 are known and I'm viewing 22.1 in the signal strength display. 16 and 20 are stupid channels I don't care about. So I want to go from 22.1 down to 13.4 to check 13. So I have to step through 20.5, 20.4, ..., 20.1, 16.4, ..., 16.1 on the way to 13. But it seems to only allow buffer up on channel down, so I have to keep stopping to wait for it to finish tuning before I can continue going down. If I instead just try going directly to 13 (such as by hitting the voice button and saying "channel 13" (voice is one thing Samsung did well), then I lose the signal strength display and have to bring it back. Fortunately, "show signal information" brings it back, but it is still kind of slow and annoying. 2. Reception at my place varies ridiculously as antenna location changes. I found that at one location I might get one set of channels. Then moving the antenna 1/3 meter I might lose a couple of those channels and get one that I hadn't got in the first position. Another 1/3 meter and another channel lineup change. With the limited tools on the TV for accessing a given location and aiming, I was not able to really explore possible locations. When an SDR comes in is that if I got one with enough bandwidth to decode ATSC TV broadcasts, it should be possible to hook that up to a laptop and make something that can show me signal strength of the channels I'm interested right at the antenna, giving much quicker and easier feedback as I change the aim and location. An ATSC channel has 6 MHz bandwidth. An RTL-SDR is only 2 MHz. It still may be possible to just look at 2 MHz of the 6 MHz channel and with sufficient voodoo figure out how good the signal is, but I don't know how to that. A LimeSDR has a bandwidth of 60 MHz. It could fully see 10 adjacent channels at once. That project got put on hold because I realized most of the places that seemed likely to be good antenna spots would be challenging when it comes to code compliant grounding of the antenna. Since then, I've bought this indoor antenna [1]. It's only marginally better than my homemade antenna, but includes a built-in signal strength meter that communicates via Bluetooth with an iOS or Android app. The built in meter scans all the channels in 6-12 seconds (way faster than my TV) and gives you a list in the app showing everything found. You can pick a channel and get a real time display for it as you aim the antenna. I can do more in five minutes with it than I could do in a couple hours using the TV. When the outdoor antenna project resumes (probably next summer...I had too many higher priority other outdoor projects this summer), I'll either take the indoor outdoors and use it to find a good outdoor antenna locations, or I'll remove the signal meter from it and use it with the outdoor antenna I made last summer. [1] https://winegard.com/products/hdtv-digital-antennas/indoor-antennas/flatwave/flatwave-amped-pro https://winegard.com/products/hdtv-digital-antennas/indoor-a...

by scrps 5y ago

tzs 5y ago

The last project for which I was considering a LimeSDR the problem with my RTL-SDR was bandwidth. Last summer I made a TV antenna and tried to find a good location for it outdoors. There were two difficulties. 1. My Samsung TV has a lousy interface for setting up an antenna. It will only let you view signal strength on known channels. By "known" I mean a channel that it found when you told it to scan for channels, or a channel that you manually tuned to and it found a sufficiently strong signal. A scan for channels starts off by forgetting all known channels. The channels here come from two different directions. This meant there was a lot of setting up the antenna and pointing it toward one group of channels, going back in the house and doing a scan, noting the signal strength for all the known channel, then going back out and turning the antenna toward the other group, coming back in and seeing what channels I still had good signal on from the known channels, and then manually tuning to the channels in the second group to see if I could get any of them well enough for them to become known. After that, there was then going back out, and systematically trying different antenna aiming to find some direction that gets me the best compromise between the two directional groups. When viewing the signal strength display, you can only change channels with channel up/channel down, which steps through all the sub-channels. The stupid Samsung interface has almost no command buffering, so suppose channels 13, 16, 20, and 22 are known and I'm viewing 22.1 in the signal strength display. 16 and 20 are stupid channels I don't care about. So I want to go from 22.1 down to 13.4 to check 13. So I have to step through 20.5, 20.4, ..., 20.1, 16.4, ..., 16.1 on the way to 13. But it seems to only allow buffer up on channel down, so I have to keep stopping to wait for it to finish tuning before I can continue going down. If I instead just try going directly to 13 (such as by hitting the voice button and saying "channel 13" (voice is one thing Samsung did well), then I lose the signal strength display and have to bring it back. Fortunately, "show signal information" brings it back, but it is still kind of slow and annoying. 2. Reception at my place varies ridiculously as antenna location changes. I found that at one location I might get one set of channels. Then moving the antenna 1/3 meter I might lose a couple of those channels and get one that I hadn't got in the first position. Another 1/3 meter and another channel lineup change. With the limited tools on the TV for accessing a given location and aiming, I was not able to really explore possible locations. When an SDR comes in is that if I got one with enough bandwidth to decode ATSC TV broadcasts, it should be possible to hook that up to a laptop and make something that can show me signal strength of the channels I'm interested right at the antenna, giving much quicker and easier feedback as I change the aim and location. An ATSC channel has 6 MHz bandwidth. An RTL-SDR is only 2 MHz. It still may be possible to just look at 2 MHz of the 6 MHz channel and with sufficient voodoo figure out how good the signal is, but I don't know how to that. A LimeSDR has a bandwidth of 60 MHz. It could fully see 10 adjacent channels at once. That project got put on hold because I realized most of the places that seemed likely to be good antenna spots would be challenging when it comes to code compliant grounding of the antenna. Since then, I've bought this indoor antenna [1]. It's only marginally better than my homemade antenna, but includes a built-in signal strength meter that communicates via Bluetooth with an iOS or Android app. The built in meter scans all the channels in 6-12 seconds (way faster than my TV) and gives you a list in the app showing everything found. You can pick a channel and get a real time display for it as you aim the antenna. I can do more in five minutes with it than I could do in a couple hours using the TV. When the outdoor antenna project resumes (probably next summer...I had too many higher priority other outdoor projects this summer), I'll either take the indoor outdoors and use it to find a good outdoor antenna locations, or I'll remove the signal meter from it and use it with the outdoor antenna I made last summer. [1] https://winegard.com/products/hdtv-digital-antennas/indoor-antennas/flatwave/flatwave-amped-pro https://winegard.com/products/hdtv-digital-antennas/indoor-a...