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Some question about VOX

Posted: Wed Jul 25, 2012 10:21 pm
by jiang319
Hi evreyone, somebody ever uesed VOX(Voice Operated Switch)? It seems VOX has some significant disadvantage such as sensitivity. Do you think it would be a much useful functionality if regardless of the issue caused by sensitivity?

Re: Some question about VOX

Posted: Wed Jul 25, 2012 10:29 pm
by Bill_G
VOX is not easily used. You have to judge it product by product. Some seem to work well, and others do not. For example, most logging recorders are VOX activated, and in general they work adequately. On the other hand, VOX activated PTT in racing radios can be a coin toss. it is troublesome technology at best.

Re: Some question about VOX

Posted: Wed Jul 25, 2012 11:30 pm
by jiang319
Bill_G wrote:VOX is not easily used. You have to judge it product by product. Some seem to work well, and others do not. For example, most logging recorders are VOX activated, and in general they work adequately. On the other hand, VOX activated PTT in racing radios can be a coin toss. it is troublesome technology at best.
if VOX hardly be impacted by external noise, would you prefer VOX or PTT pressing?

Re: Some question about VOX

Posted: Thu Jul 26, 2012 5:17 am
by Bill_G
I prefer pressing a PTT button.

Re: Some question about VOX

Posted: Thu Jul 26, 2012 6:04 am
by Tom in D.C.
VOX finds it's best application in HF radio when you're sitting at a desk in a quiet room. All VOX systems, at least in the ham HF radios, have adjustments for sensitivity and a few other things whose names I forget, and the settings fit one person only. If someone else takes the mic to talk the adjustments made previously may or may not word satisfactorily. For pure reliability in a noisy/mobile/portable environment PTT bests VOX by a mile.

Re: Some question about VOX

Posted: Thu Jul 26, 2012 5:07 pm
by Jim202
jiang319 wrote:Hi evreyone, somebody ever uesed VOX(Voice Operated Switch)? It seems VOX has some significant disadvantage such as sensitivity. Do you think it would be a much useful functionality if regardless of the issue caused by sensitivity?



There are some applications where a VOX circuit is used in conjunction with an audio delay. In at least one radio interoperability gateway I know of uses a combination of the VOX and the audio delay. The delay is on the mic audio to delay it enough that the key up of the radio happens and then the audio is sent. It only takes about 120 to 200 milliseconds to keep from loosing an entire short word. This prevents the all too well known problem of chopping off the very start of the voice. If done carefully, you will get the entire word and not just the last half of it. There is a big difference between hearing shoot and "don't" shoot.

Re: Some question about VOX

Posted: Thu Jul 26, 2012 8:15 pm
by Bill_G
Oh come on Jim. I like starting every sentence with uuuuuh.

uuuuuh Jim (skirtch)
uuuuuh yeah Bill, go ahead (skirtch)
uuuuuh you want me to drop this load here? (skirtch)
uuuuuh over a little more, little more, little more, K! (skirtch)

Re: Some question about VOX

Posted: Fri Jul 27, 2012 6:24 am
by Tom in D.C.
Bill,

Excellent, and funny, reminder of my 75-meter SSB days. If you
forgot that "Uhhhh" to start with you always, always, lost a word.

Regards,

Re: Some question about VOX

Posted: Fri Jul 27, 2012 8:18 am
by Bill_G
Tom - (snort) Have you ever listened to race car traffic? Some have a PTT, and some have VOX. You can always tell who is VOX.

Re: Some question about VOX

Posted: Fri Jul 27, 2012 5:08 pm
by Will
Bill_G wrote:I prefer pressing a PTT button.
And don't forget to set the Time Out Timer to one minute.