You need to also check out the ARRL product review on this unit. While the published specs show it operating in a 2.5khz bandwidth, the ARRL measured bandwidth was actually almost 3.25khz for the unit itself. For some reason, which the ARRL did not go into, the noise from the unit above the last carrier from the unit is very high. It is only down 20db at 3khz and it is out to 3.25khz before it dissipates down to -26db. While the SSB filter in a typical transmitter will knock this down quite a bit, it must be considered when stating the actual bandwidth. I would expect, with a typical 2.8khz SSB filter (-6db) points, the transmitted bandwidth for the AOR unit will look much like that of a SSB transmission.
Two main considerations usually apply when considering equipment purchases: 1. Capability 2. Cost When considering the signal to noise ratio disadvantage (almost 10db) the AOR DV has plus an actual transmitted bandwidth equivalent to SSB, it has little to offer over and above SSB alone. The operational characteristics must also be considered. The unit would problematic for use on traffic nets. for weak-signal work, or for DX pileups. The unit costs as much or more as an entry-level SSB transmitter, thereby doubling the costs to use the mode. While SSB may have been expensive for the initial experimenters, the cost dropped dramatically in just a few years, primarily because the manufacturers found SSB equipment cost less to make than AM equipment. More capability and less cost - it was an advantage AM couldn't beat. It will be hard for DV to reach the goal of more capability and less cost, primarily because you must have a SSB transceiver as well as the DV codec equipment. Even leaving out the analog audio chain wouldn't significantly lower manufacturing costs in a dedicated DV transceiver. I know the DV cheerleaders won't like this reality but I know I'm not going to be purchasing a DV unit any time soon. That amount of money will buy me four more 2m handitalkies or almost 1/2 of a new 746pro. If the units drop to $75 in a couple of years I might consider it then. DV *does* have an area in which it could beat SSB - high intelligibility point-to-point links between fixed sites. For some reason everyone seems to be ignoring this area, probably because the potential sales would be rather low to begin with. If the transmitted audio bandwidth were to be extended out to 4.5khz it would provide very nice links between EOC's and NGO's (e.g. Salvation Army Emergency Disaster headquarter sites or Corp sites) on HF. The high intelligibility audio coupled with low in-band noise would provide very high quality communications where fixed sites would allow engineering the links to the required signal to noise ratio. Admittedly, the bandwidth would go up, but since the links would only be used during disaster responses, the actual spectrum efficiency impacts would be minimal. The biggest question is who will finance doing this at your local SA, ARC, etc... site? tim ab0wr On Monday 06 February 2006 12:45, Danny Douglas wrote: > OK John. I had looked at the ads and read up on that before, and > immediately forgot it. The 500 bucks would go a long way toward > a new, shiney, taller tower, which mama wont let me buy anyway. Hi. > Danny > > > > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org > > Other areas of interest: > > The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ > DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy > discussion) > > > Yahoo! Groups Links > > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
