Introduction
Pole/Zero utilizes an eight-bit scheme for tune words to digitally control tuning of the center frequency across its standard product line of Bandpass filters. This eight- bit scheme is shown in the following table.
|
Tune Word |
Result |
|
00000000
thru
11111010 |
Lowest tuned frequency
(251 total tune codes)
Highest tuned frequency |
|
11111011
thru
11111110 |
RF In/Out Isolation
Filter Blanked |
|
11111111 |
Power saver mode; all PIN diodes turned off |
There are 250 equally spaced tuning increments across each standard filter band, resulting in 251 tune words from 00000000 to 11111010. The last 5 tune words are reserved for housekeeping functions:
Calculating a Tune Address:
The binary tuning word is determined by the following relationship:
Example: If you wish to tune to 322 MHz using a 225 to 400 MHz filter, the tune word is:
 (10001011 binary)
NOTE: Round off to the nearest decimal integer! | 