What is the role of frequency synthesizer stages in a receiver and transmitter?

[Underhill]

I've checked the Internet and this forum, and while I notice the term, "tuning resolution" used in different contexts, I can't find a definition. Can anyone provide a clear and concise definition or explanation?

 

[nsaspook]

We used it to describe the 'tuning' increments or discrete frequency steps of a digital receiver.

For an old receiver like the R-1051 there were several models
Some had 500hz "tuning resolution"
other models had 100hz "tuning resolution"
http://www.radiomuseum.org/r/military_radio_receiver_r_1051urr.html

The receiver joins quite exceptional performances to a marvelous modular execution, with the RF unit containing the several tuning turrets, the external one is motor driven. The exceptional frequency stability is based upon an internal 5.0 MHz frequency standard reference (An external standard may be selected) and a synthesizer, phase locked to the reference, also containing an error canceling loop. Various revisions built in the years, with increasing tuning resolution. Depending upon the revision, varies the quantity of semiconductors (Transistors and even ICs) used.

http://www.navy-radio.com/rcvrs/r1051.htm

 

[nsaspook]

A cool note about this receiver. The RF front end still used tubes for nuke EMP protection and for protection from high RF input levels when operated near high-power HF transmitters.
http://www.navy-radio.com/rcvrs/r1051/r1051-02.jpg

The frequency synthesizer stages were also used in the matched transmitter.
http://www.boatanchors.org/URT-23images/URT23xa.jpg