SignalScopePage » History » Version 5
max, 04/22/2017 04:04 PM
| 1 | 1 | max | = Signal Scope = |
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| 2 | |||
| 3 | == Installation == |
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| 4 | |||
| 5 | Before running the scope app, check that the following packages are also installed: |
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| 6 | * GNU Radio |
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| 7 | * The op25 blocks |
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| 8 | * Frank's gr-fsk4 block |
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| 9 | * The op25 repeater block |
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| 10 | |||
| 11 | Other than these pre-requisites, no special setup or installation is needed. |
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| 12 | |||
| 13 | 5 | max | There are three overall options or modes depending on your hardware; these are |
| 14 | * USRP |
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| 15 | * External receiver with discriminator tap connected to sound card |
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| 16 | * External receiver with IF in the audio sound card range (e.g., 24 KHz), referred to as "audio IF" |
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| 17 | 3 | max | |
| 18 | 1 | max | == Running with the disc-tap option == |
| 19 | |||
| 20 | The signal scope does not require the USRP. If you have a discriminator-tapped receiver, use the "-a" option: |
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| 21 | 3 | max | {{{ |
| 22 | 5 | max | ./scope.py -a -v 25 -g 50 |
| 23 | 3 | max | }}} |
| 24 | |||
| 25 | == Running with the USRP == |
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| 26 | |||
| 27 | It's helpful to find out the current calibration error beforehand (I use kalibrate), for example, +1234 hertz: |
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| 28 | {{{ |
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| 29 | 1 | max | ./scope.py -f 412.34e6 -RA -g 65 -c 1234 -v 25 |
| 30 | 3 | max | }}} |
| 31 | 1 | max | |
| 32 | 5 | max | == Running in the Audio IF mode == |
| 33 | 1 | max | |
| 34 | 5 | max | Receivers equipped with an IF output in the sound card range can be used. This is known as "audio IF" mode. |
| 35 | A soundcard sampling rate of 96K is used and the IF frequency (typically 24 KHz) is given using the {{{--calibration}}} parameter: |
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| 36 | |||
| 37 | {{{ |
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| 38 | ./scope.py -A -c 24e3 -g 50 -v 25 |
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| 39 | }}} |
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| 40 | |||
| 41 | 4 | max | == Feature overview == |
| 42 | |||
| 43 | * Spectrum plot |
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| 44 | * Baseband oscilloscope |
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| 45 | * Eye Pattern Diagram (Datascope) display supporting several standard symbol rates |
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| 46 | * Constellation Diagrams |
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| 47 | * Demodulated Symbol Output |
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| 48 | 1 | max | * Correlation |
| 49 | * Direct-frequency entry, signal gain and fine-tuning controls |
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| 50 | * User-selectable demodulator (FSK4 or QPSK) |
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| 51 | 5 | max | |
| 52 | In the USRP and audio-IF modes, several additional program functions are enabled (spectrum FFT, constellation diagram, PSK demod, and iDEN correlation). |
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| 53 | |||
| 54 | In all modes, the {{{--wireshark}}} option is used to write received P25 packet data to Wireshark. |
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| 55 | 4 | max | |
| 56 | == Spectrum Display == |
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| 57 | |||
| 58 | [[Image(a.png)]] |
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| 59 | |||
| 60 | The controls arranged along the bottom of the page are: |
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| 61 | * Frequency: to retune, type the new frequency here and press ENTER |
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| 62 | * Signal Gain: adjusts the baseband (demodulated) signal level |
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| 63 | * Fine Tune: adjusts tuning frequency over +/- 3000 Hz range |
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| 64 | * Demod: Selects demodulator (currently used in Demodulated Symbols only) |
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| 65 | Except for the signal gain control, these controls are only available in USRP RX mode. |
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| 66 | |||
| 67 | == Eye Pattern Diagrams == |
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| 68 | |||
| 69 | The scope input source can be connected either before or after the symbol filter using the Viewpoint toggle. |
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| 70 | |||
| 71 | Also the proper speed must be selected from the available options. |
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| 72 | |||
| 73 | [[Image(b.png)]] |
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| 74 | |||
| 75 | == Constellation Diagram == |
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| 76 | |||
| 77 | [[Image(c.png)]] |
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| 78 | |||
| 79 | == Demodulated Symbols == |
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| 80 | |||
| 81 | [[Image(d.png)]] |
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| 82 | |||
| 83 | == Correlation == |
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| 84 | |||
| 85 | [[Image(e.png)]] |
