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#1
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SDR dongles, et al?
First question is, that when TV tuners are pressed into service, what is it
the comes digitised down the USB cable? Is it chunks of spectrum downconverted in 6M5Hz chunks to suit the TV channels, or are they capable of finer tuning than that? Secondly, do they have a good dynamic range? Thirdly, when narrow filtering is being synthesized in the PC, is it IF filtering (good) or AF filtering (tends to ring for 20WPM +) ? Fourthly, with the SDR and oscillator kits available from www.sdr-kits.co.uk, will the day shortly be here when all _REAL_ radio amateurs will be eqipped with a speccy-plus-tracking-generator at a fraction of the cost of traditional professional models? (But not talking of the £200+ hidden cost of the PC to drive it) |
#2
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SDR dongles, et al?
On 27/12/2015 18:46, gareth wrote:
First question is, that when TV tuners are pressed into service, what is it the comes digitised down the USB cable? Is it chunks of spectrum downconverted in 6M5Hz chunks to suit the TV channels, or are they capable of finer tuning than that? Secondly, do they have a good dynamic range? Thirdly, when narrow filtering is being synthesized in the PC, is it IF filtering (good) or AF filtering (tends to ring for 20WPM +) ? [] Gareth, The RTL devices can be tuned fairly precisely IIRC, certainly a few hundreds of Hz and possibly tens of Hz. They are not limited to TV channelling. In normal mode, what comes over USB are digital TV packets, as the RF to digital decoding is built into the RTL chip set. Amateur use is a special debugging mode, where 8-bit I and Q packets are sent over the USB instead. 8 bits is the dynamic range, adequate for a few strong broadcast signals, but not for weak signal work in the presence of large signals. They are also broadband devices and may need very good front-end filtering in RF-rich areas. If you need a good dynamic range, consider an SDRplay, FunCube or AirSpy/SpyVerter instead which digitise to more than 8 bits. http://www.sdrplay.com/ http://www.funcubedongle.com/ http://airspy.com/ but not the FunCube for LF work (below about 1 MHz) as it gets very insensitive! With PC processing, it's your choice of IF or AF filtering. Look at the specs for the different DSP programs available - HDSDR, SDR#, SDR Console etc. The RTL dongles are fun to play with, and a useful introduction to SDR. |
#3
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SDR dongles, et al?
In article , David Taylor wrote:
The RTL dongles are fun to play with, and a useful introduction to SDR. You forgot to copy & paste the .sig OM. |
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