G8JCFSDR Build 282 - Release Notes

[g8jcf]

Release Notes Build 282

Build 282 has many fixes and new features - see the QuickStartGuide for more details.

Higher IF sampling rates of :

• 48000 48KHz spectrum display width

• 96000 96KHz spectrum display width

• 192000 192KHz spectrum display width

• 384000 384KHz spectrum display width

assuming that your sound card can support these higher rates – every soundcard I have used supports 48000, and most support 96000, with some supporting 192000, and very few (very expensive) supporting 384000.

Note that the AF output sampling frequency is always 48000 samples/second enabling one to use the inbuilt soundcard and speaker(s) of your system whilst using a higher specification sound card to capture the IF output from the SDR down converter.

Synchronous AM Demodulation.
SAM. SAM demodulation can be of help when fading, QSB, causes the AM carrier to almost disappear into the noise. Also, when there is adjacent channel interference. QRM, SAM can be useful to select the opposite sideband to the one being interfered with.

• SMD SAM Double Sideband, ie both sidebands used

• SMU SAM Upper Sideband

• SML SAM Lower Sideband

The SAM lock indicator will light up green when the G8JCFSDR’s internal numerically controlled oscillator is locked to the AM carrier.

Additional Calibration Functionality
The SDRShield calibration window in Config has been augmented to provide additional functionality including an improved frequency calibration method.

The IQ Cal Freq facility when switched on generates a carrier 1 KHz higher up from the current tuned frequency on CLK0 of the SI5351.

If you have a V 2 SDRShield then attach a short length, eg 30cm, of wire to the CLK0 header pins.
If you have a V1 SDRShield then very good soldering skills are required if you want to use this facility, ie not recommended.

Follow the procedure for IQ balance/Image rejection described in Quick Start Guide section 4.7.

The SMeter Cal Freq when switched on generates a 10 KHz square wave on CLK2 of the SI5351 as described in Burkhard Kainka’s book, 7.2, “SDR Hands-on Book”. The output from CLK2 is 3V3 pk-pk or 1.65 V RMS. SMeter levels are measured in micro-volts, uV, so we have to use an attenuator (see below)), and the fact that square waves are rich in harmonics to generate signals in the uV range at HF. This arrangement will generate an S9 (50uV) signal at 7MHz, S8 at 14MHz, S7 at 28MHz.

Rotary Encoder Tuning, 1602 I2C LCD
Use a rotary encoder for real hardware/knob tuning, and optionally an LCD for frequency display.

Connect a rotary encoder, eg ALPS EC16B2410408 RS 265-1723, A & B to pins 2 & 3 respectively and to OV.

Connect a 1602 I2C LCD, eg https://hobbycomponents.com/displays/74 ... 602-module or of course eBay, to pin A4(SDA) and pin A5(SCL), you will also need to connect Vcc and GND to the I2C LCD module of course.