Архив за 13.10.2018

Other SDR Devices • Re: Why Tx/Rx devices are so expansives ?

rtlsdrblog wrote:
Fri Oct 12, 2018 6:36 am
I assume that in the future all smartphones will be using SDR based radios.
Disagree. Current smart phones can already do CDMA/GSM/LTE with traditional ASICs at a reasonable price, so aside from upgradeability and additional flexibility, there is not a whole lot to gain by using an SDR instead. And as you've correctly mentioned, such a phone would likely to use more power, which would be a *major* no-no.
But that does use more battery and CPU power, and no guarantees that they'll be hackable into general purpose receivers.
Hacking them to general purpose receivers would likely require both FW and HW mods, and doing the latter on phones will likely require some exceptional soldering skill.
kelegaya wrote:
Wed Oct 10, 2018 5:00 pm
So sorry, i'm a beginner, but i was thinking " Why don't they extract GSM chip of those cheap smartphone to do their usb transceiver"...
Because they contain ASICs (Application Specific Integrated Circuits) that are designed to send/receive (code/decode) GSM/CDMA/LTE/etc., and the phones cannot be easily modified to be used as general purpose transceivers. I presume that in some cases it could be possible to modify them with some kind HW mod, but those mods are not easy to do.
How can a constructor provides smartphones at 40€ with Tx/Rx capability and other cool stuff integrated like wifi, bluetooth, keyboard, operating system etc...
Because they use a handful of ICs that can be very cheap when you are making millions. In addition, I think the lowest frequency mobile phones is currently 600 MHz, (there were lower frequencies used before, but not any more) so the RF chips used in the phones don't need to go down very much. Also, handsets can be sold under cost and subsidized by carriers, so the price you see may not always reflect the true cost.

Statistics: Posted by aurgathor — Sat Oct 13, 2018 11:49 pm


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fox-nsk пишет:
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Troubleshooting Help • Re: RTL-SDR v3 direct sampling over a network

Ok, so I just fired up gqrx on linux box, and after a little searching the web you now use direct_samp=3
Save the config and relaunch. I'm using gqrx 2.11.5
I'm still on the Lan though but at least the see signals...lots of them today for a change....contesting.
Hope this helps......anything other than 3 ...gqrx blows away

Statistics: Posted by tim_rtd — Sat Oct 13, 2018 9:21 pm


Antennas • Re: The best antenna I have tested till now

Congratulations on your new antenna! :D I'm about 35 miles away from the big antennas with line of sight but my reception is weak on a lot of channels. I did some research and came upon the Antennas Direct DB4 antenna and the horde of hobbyists that have copied the design using coat hangers. It looks cool and a lot of people seem happy with the performance. Have you ever built this antenna with success before? I'm looking to make one myself

Statistics: Posted by MathewCox — Sat Oct 13, 2018 9:04 pm


I have a ~3 meter long coaxial cable and I would like to make a dipole antenna for listening to the 20m band, is it realistic?

I have a ~3 meter long coaxial cable and I would like to make a dipole antenna for listening to the 20m band, is it realistic? submitted by /u/GeoGemstones
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WXtoImg: Could not find matching pass to build overlay map

I would like to use WXtoImg's map overlay function, however the program seems incapable of detecting the satellite pass that the recording is from. I use Linux Mint, and the satellite in question was NOAA 19.

I have:
- set my lat/long into the ground station location
- set proper file name/template
- used the 'touch -t' command to manually set the time stamp of the audio file (I tried both UTC and local)
- updated the keplers
- switched to advanced mode and manually set the direction and satellite

I did, however, notice that the 'mouse' coordinates in WX are still off, even when it says that the pass was detected (and it shows the matching info). I have used the registration code available on the wxtoimgrestored.xyz website.

This is the image from the recording, if it's of any use: https://imgur.com/UEchhUw (it's part of Europe)

submitted by /u/derekcz
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Comment on Scanning the Spectrum at 8GHz per Second with the new HackRF Update by zhang

Hello brother, would you use this software? Please contact me in my email

Troubleshooting Help • Re: RTL-SDR v3 direct sampling over a network

only reason I was using a lower sample rate is because I'm using wifi and I found if I used anything much more above than what I chose the audio would break up. Is my sampling rate too low and freq shift setting is there one for rtL_tcp? (If it is the same thing there's a second frequency reading in GQRX which I usually leave on 0 Khz as opposed to the actual freq. just above the waterfall).

Update: I gave using the low sample rate along with using USB direct (as opposed to using wifi). I used these settings with the USB (RTL SDR v3) directly connected into the pc running GQRX:

- device string = rtl=0,direct_samp=2
- input rate=240000

Those should duplicate my raspberry pi/rtl_tcp settings. Tried out normal AM radio and it works but only via a direct USB connection.

Still not working with rtl_tcp though x.x ! Can't help but think maybe either GQRX needs to send *something* to rtl_tcp or maybe a setting in rtl_tcp?

Random thought: prehaps -D 2 in rtl_tcp needs to be specified first? (the way the rtl sdr gets *nothing* on the pi with rtl_tcp makes me think maybe direct sampling isn't working....just a thought).

ljones

Statistics: Posted by ljones — Sat Oct 13, 2018 6:26 pm


Troubleshooting Help • Re: RTL-SDR v3 direct sampling over a network

I've duplicated your setup with a Pi and V3 dongle using the rtl_tcp -a xxx xxx xxx xx -D 2. I'm listing to the 20M band at the moment and its working...Using SDR #.... I would say to you from looking a previous post that for some reason your using a very low sampling rate of 204Khz instead of 2.4Mhz....and turn off any freq shift setting. Also I'm using the lan....

Statistics: Posted by tim_rtd — Sat Oct 13, 2018 4:00 pm


What is this signal?

Does anyone know what this signal is ?

Its about 20k in width and there are a few of them in and around all of the DMR channels in the 20m band but DSD cannot decode them.

submitted by /u/sudohash
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