AN115: 505DSP And Logging Programs

1. Introduction.

Beginning with 505DSP firmware V3.x3, the transceiver supports the interrogation of frequency, mode, and transmitter power as required by most PC-based logging programs. Commands have been added to the Interface Specification V.Q33 for this purpose, as outlined below.

2. Getting RX Frequency Information.

In keeping with the Kachina control protocol (q.v.), RX frequency interrogation is achieved by sending the following command:
(STX) "b" (37H) (ETX)

The transceiver responds with an acknowledgement byte (FFH), followed by the frequency in the block format shown below:
(FDH) (aa) (bb) (cc) (dd) (ee) (ff)

Concatenated bytes (aa:bb:cc:dd) contain the frequency and antenna port data. Concatenated bytes (ee:ff) are a 16-bit checksum value, found by adding all the previous bytes in the block together:
ee:ff=aa+bb+cc+dd

Bits 7 and 6 of byte (aa) contain the antenna port data as shown below:
0 0 = TX on B, RX on A
0 1 = TX on A, RX on A
1 0 = TX on B, RX on B
1 1 = TX on A, RX on B

To find the frequency in hertz, ignore these two bits and use the least-significant 28 bits in the following formula:
F(Hz) = [0.4470348358221 * (aa:bb:cc:dd)] -75,000,000

This shows that the internal synthesizer moves in 0.447035 Hz steps.

3. Retrieving the Mode Setting.

The transceiver's current mode setting may be retrieved by sending the command:
(STX) "b" (38H) (ETX)

The mode is returned in a data packet beginning with the acknowledgement byte (FFH), followed by:
(FDH) (aa)

where (aa) is:
01 = AM
02 = CW
03 = FM
04 = USB
05 = LSB

4. Retrieving the Power Setting.

The transmitter's current maximum power output setting may be retrieved by sending the command:
(STX) "b" (39H) (ETX)

The power setting is returned in a data packet beginning with the acknowledgement byte (FFH), followed by:
(FDH) (aa)

where (aa) is the setting in watts.