A much more applicable comparison would be to look at testing of P25 digital voice radios versus testing of D-Star radios.
In fact, as you note, many tests on digital capable radios are the same as the tests performed on analog FM transceivers. This also applies to radio alignment. For example, the Motorola Astro Spectra and XTS series radios have a number of alignments which must be performed so that the radio will operate optimally in both analog FM and digital voice systems. All of these alignments can be performed with traditional analog test instrumentation. However, alignment is one thing, performance verification is quite another. The P25 standard defines many tests which verify the performance of these radios in digital mode. [See TIA-102.CAAA-B and TIA-102.CAAB-B] Some of these tests are undoubtedly of more interest to manufacturers than to end users, but many are important in the field. Examples would be modulation fidelity, reference sensitivity, BER and so on. The importance of these tests resulted in the development of digital service monitors such as the General Dynamics R2670 and the IFR/Aeroflex 2975. Unlike your DPL example, receiver IF charistics for analog FM and digital voice operating modes may very well be different, even in the same radio. This affects receiver sensitivity, IM rejection, co-channel and adjacent channel rejection, etc. These characteristics ARE of significant interest to those who service and support digital systems - if they were not - no one would buy the digital service monitors. Amateurs are also interested in these radio performance parameters, particularly those who are interested in the development of band plans [channel spacing, frequency re-use, etc.]and those who want to implement repeater systems that perform optimally. Unfortunately, the D-Star standard does not appear to contain any provision for making tests in the digital domain. So, if I want to verify the effective receiver sensitivity and desensitization of a P25 digital repeater - with a laptop, service software, and a digital service monitor, I can do just that. If I want to verify the performance of a D-Star repeater - operating in its native digital mode - I can't. Although there was a product announcement from Aeroflex with respect to testing of D-Star radios - that referenced an autotest software package to be developed for Icom. There are two things that are significant about that. If you contact Aeroflex, you will find that the announcement really only refers to an agreement. No product exists at this time nor is there even a set of functions defined yet. Second, it is probable that the auto alignment of the Icom radios - just as the alignment of Motorola P25 radios - really only adjusts certain analog parameters. Hopefully, Icom and Aeroflex go beyond that to include some sort of digital mode tests but don't look for that product any time soon. --------------------------------------------------------------------- --- In [email protected], "Steven Samuel Bosshard (NU5D)" <bossh...@...> wrote: "Motorola developed Digital Coded Squelch (their Digital Private Line or DPL) in band subaudible selective squelch system. ... Much like DSTAR, radio servicing stayed the same. ...Rf and IF amps were the same given the operating bandwidths involved. The only big difference was testing the squelch ...Much applies to a DSTAR radio. ..."
