For older style RadioTrack cards only.

This function tunes the old-style RadioTrack cards to the given frequency. The format of the function is:

return_data = RT1Freq( rt_address, freq, fine_tune )

The rt_address is the decimal value of the card's I/O location 780 (30C hex) or 524 (20C hex).

freq is the frequency in MHz x 10. Tuning to 90.1MHz would mean freq must be set to the decimal integer 901. Note: Valid frequency range is 87.0MHz to 109.0MHz. No range check is performed in rxRTCtrl.DLL.

fine_tune allows to fine tune the set frequency freq in steps of 0.025MHz. fine_tune has possible values of 0, 1, 2, 3, 4, -1, -2, -3 and -4. A value of 0 means there is no fine tuning requested and the set frequency would be as given by freq. A value of 1 would add 0.025 MHz to freq before the frequency is actually set in the card. A value of -1 would subtract 0.025 MHz from freq before the frequency is actually set in the card. Similarly, 2 corresponds to adding/subtracting 0.05MHz, 3 to 0.075MHz and 4 to 0.1MHz. There is not value check of the fine_tune parameter, so you must assure it stays within the range given.

return_data returns the following values:

0 No errors.
1 Frequency can't be tuned.
10 TESTCFG.SYS could not be opened.

Note: Scanning for stations can be implemented by setting the frequency to a certain value then wait for a few seconds, increment to the next frequency and so on. When a station is found, you can either use the function RT2Tuned (newer RadioTrack only) or provide a way to manually stop scanning.