[hpsdr] TeamSpeak audio 2009/Sep/19

[Jeremy McDermond]

Just a quick comment on the discussion Phil was having regarding the  
packet size on the PHY on OZY II.  You for sure don't want to be  
sending packets > 1500 bytes across the wire (mini-jumbos or jumbos)  
because much of the consumer grade switching equipment can't handle  
jumbo packets.  Honestly, jumbo support on enterprise and service  
provider equipment is spotty.  My Cisco 12000 series router has jumbo  
issues.  Either that, or you may want to think about having a switch  
to enable jumbos for users that know that they have networking  
equipment that will support it.

The other consideration regarding this is that if you're running  
jumbos on IP, you're going to have people go into their network  
settings to change the MTU on their PC (or Mac's) Ethernet interface  
in order to transmit packets above the default of 1500 bytes.  This  
could cause some issues because you're going to have to have them  
change the MTU on their entire network to support this.  This could  
cause more headaches than you're willing to deal with.

Just some thoughts.

As far as performance of Mercury, which was discussed later.  I saw  
that there are some performance numbers on TAPR's Mercury page, I'm  
not sure if they're at all accurate or where they came from:

	• ADC overload: -12dBm (preamp on), +8dBm (preamp off)
	• MDS (500Hz), 160m - 6m: -138dBm (preamp on), -118dBm (preamp off)
	• IP3 equivalent (independent of spacing): +33dBm (preamp on), > 
+50dBm (preamp off)
	• BDR (5kHz, 1dB GC): -119dBm (ADC overload limited, not phase noise  
limited)
	• 122.88MHz clock phase noise: -149dBc/Hz at 1kHz spacing

http://www.tapr.org/kits_merc.html

--
Jeremy McDermond (NH6Z)
Xenotropic Systems
mcdermj at xenotropic.com



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