OP25j

= Signal Scope =

== Installation ==

Before running the scope app, check that the following packages are also installed:

 * GNU Radio

 * The op25 blocks

 * Frank's gr-fsk4 block

 * The op25 repeater block

Other than these pre-requisites, no special setup or installation is needed.

There are two overall options depending on your hardware (USRP or disc-tap).

== Running with the disc-tap option ==

The signal scope does not require the USRP.  If you have a discriminator-tapped receiver, use the "-a" option:

{{{

./scope.py -a -v 25

}}}

== Running with the USRP ==

It's helpful to find out the current calibration error beforehand (I use kalibrate), for example, +1234 hertz:

{{{

./scope.py -f 412.34e6 -RA -g 65 -c 1234 -v 25

}}}

In USRP mode, several additional program functions are enabled (spectrum FFT, constellation diagram, PSK demod, and iDEN correlation).

== Feature overview ==

 * Spectrum plot

 * Baseband oscilloscope

 * Eye Pattern Diagram (Datascope) display supporting several standard symbol rates

 * Constellation Diagrams

 * Demodulated Symbol Output

 * Correlation 

 * Direct-frequency entry, signal gain and fine-tuning controls

 * User-selectable demodulator (FSK4 or QPSK)

== Spectrum Display ==

[[Image(a.png)]]

The controls arranged along the bottom of the page are:

 * Frequency: to retune, type the new frequency here and press ENTER

 * Signal Gain: adjusts the baseband (demodulated) signal level

 * Fine Tune: adjusts tuning frequency over +/- 3000 Hz range

 * Demod: Selects demodulator (currently used in Demodulated Symbols only)

Except for the signal gain control, these controls are only available in USRP RX mode.

== Eye Pattern Diagrams ==

The scope input source can be connected either before or after the symbol filter using the Viewpoint toggle.

Also the proper speed must be selected from the available options.

[[Image(b.png)]]

== Constellation Diagram ==

[[Image(c.png)]]

== Demodulated Symbols ==

[[Image(d.png)]]

== Correlation ==

[[Image(e.png)]]