GNC 255 Pireps?

Hi,

Anyone out there with a 255 that would like to give a Pirep on the radio, and especially the intercom function?

If the pilot, or passenger, is speaking on the intercom and a transmission comes in on the primary frequency does the intercom mute giving the primary freq priority? If so can this be changed in the setup so it does not mute?

Same question with the standby monitoring and a something comes in on the primary?

If it can be set up where there is no mute, can volumes be set differently for the intercom and standby monitor? Higher volume on primary and secondary not muting, but lower volume in the background? Same for the intercom?

I have watched YouTube demos and have done searches, but still not sure how it does it.

Thanks
Mark

Hello Mark,
the intercom in the new GNC 255 will not mute the Intercom when transmission is received on the main or monitored comm. frequency. This is also the same with the monitored and active comm. frequencies. The GNC 255 only has one receiver so it will switch back and forth between the primary and monitored comm frequencies, so you will only hear one at a time. This is also not configurable to do so in the configuration modes.
you can also adjust the intercom volumes separately from the Comm. volumes.

Let me know if there are any other questions,

you gotta be kidding!

so, when you monitor a second frequency and there is some chat there ongoing, you automatically miss the important ATC call on #1?!
absolutely useless feature in that case!
#1 has to have priority at all times.

heck, the SL30 which is like 20 years old and which the GNC255 was supposed to replace does better than that. extremely poor design choice from my (both ATC controller and SL30 user) point of view :-(

sorry for the rant.

there's little that we controllers hate more than pilots not responding quickly. now they may not because it doesn't work like it used to with the sl30.

regards,
bernie

Page 2-2 of the user manual states similar functionality as the SL series.

I don't think you have anything to worry about.

GNC 255 Pireps

I don't mean to hijack this thread but this is a good opportunity to ask a question I have had on my mind for a while. Does Garmin (or anyone else) make a certified NavComGPS radio without a moving map? I've surfed their site with no luck. I have a Dynon SV-1000 w/ADS-B and an iFly 720 and don't want to pay extra for a poorly designed "me too" display on a radio. Dan

Thanks for the replies.

Copy and pasted from the manual:
"When the Active frequency receives a signal, the unit will switch automatically to the Active frequency. The Active frequency quality is not affected."

This is why I asked the question. I believe the above statement is misleading and TrekLawler has helped clarify.

I believe (I'm no techie though) what the radio does is use one receiver to bounce between the two freq's (only during the monitor function) to find a transmission to latch onto. So, in my mind, the active frequency will never "receive a signal" regardless of whether there have been many come over, until the secondary no longer receives what it latched on to, and releases itself to listen to the primary again. If listening to an ATIS in an endless loop on the secondary, the pilot would unwittingly have put himself off frequency for as many loops as he needs to get the data, all the while thinking he didn't miss anything on the primary because it was quiet. (For him anyway)

If this is not how it works, please re-educate me.

I am not a fan of this feature if this really is how it works, but do understand the cost savings with only having one receiver. I am happy the intercom does not mute while the radio receives. For me that has always been more distracting. I just wish the price point on a 430w was in the ballpark of a 400w +GNC 255.

Mark

Standby Frequency Monitoring

RV Wannabe said:

Copy and pasted from the manual:
"When the Active frequency receives a signal, the unit will switch automatically to the Active frequency. The Active frequency quality is not affected."

I believe (I'm no techie though) what the radio does is use one receiver to bounce between the two freq's (only during the monitor function) to find a transmission to latch onto. So, in my mind, the active frequency will never "receive a signal" regardless of whether there have been many come over, until the secondary no longer receives what it latched on to, and releases itself to listen to the primary again. If listening to an ATIS in an endless loop on the secondary, the pilot would unwittingly have put himself off frequency for as many loops as he needs to get the data, all the while thinking he didn't miss anything on the primary because it was quiet. (For him anyway)

Click to expand...

Hello Mark,

You are correct that the radio does just use one receiver, but the rest of the description isn't accurate.

When standby frequency monitoring is active, the radio is constantly sampling both frequencies and looking for receive activity.

If receive activity is sensed on the active frequency, the radio suspends this sampling activity and monitors only the active frequency until it is no longer active and then goes back to sampling both frequencies.

If receive activity is sensed on the standby frequency, the radio provides the received signal to the pilot as clearly as possible, but continues to sample the active frequency since it is always considered to be a higher priority than the standby.

So, for the example where you are monitoring ATIS on the standby and then receive a transmission from the tower on the active frequency, the radio will automatically suspend listening to ATIS, and focus 100% on the active frequency as long as it is being received.

You should never miss a radio transmission coming in on the active frequency no matter how busy the standby frequency is.

Let us know if this doesn't clear things up.

Thanks,
Steve

As the above post stated, the new Garmin radio monitors a second com frequency just like the SL-30 does. But, as best I can determine (Is this correct??), it will not monitor, and display the radial or bearing to, a second VOR, like the SL-30 does. This is too bad; with more and more aircraft going to a single nav radio, this function is quite useful.

Ok, thanks for clarifying. That makes sense on the radio side.

It is a little bit of a misnomer on the "standby monitor" term though.. It is only "monitoring" when there is nothing on the primary freq since something has to give. The standby is getting "muted" (my term, obviously not technically accurate) when the primary is receiving. Kind of standby "occasional" monitoring I don't really like it, but can live with it for the price point.

Just to clarify though, the intercom does NOT do this? If something comes in over the primary, the backseat pax does NOT drop out mid sentance for radio priority??

Thanks for the input
Mark

To the best of my knowledge, there are intercoms which mute music when the radio is active, but I've never seen one that mutes the intercom function. As a cfi I wouldn't want the radio to interupt my lecture! Many intercoms let you select 'pilot only' if you do not want to hear the passengers, but that feature is not activated by radio transmissions.

I think you have the com monitor function figured out. If there is a signal on the active frequency then it does not monitor. If no signal on the active, it does monitor the standby frequency, and will switch if there is a signal. While on the standby frequency it does monitor the active frequency, and will switch back to it if a signal comes in.

RV Wannabe said:

Ok, thanks for clarifying. That makes sense on the radio side.

Just to clarify though, the intercom does NOT do this? If something comes in over the primary, the backseat pax does NOT drop out mid sentance for radio priority??

Thanks for the input
Mark

Click to expand...

Hello Mark,

Yes, that is correct. The intercom is not muted when receiving COM audio from either the active or a monitored standby frequency.

Thanks,
Steve

RV Wannabe said:

It is a little bit of a misnomer on the "standby monitor" term though.. It is only "monitoring" when there is nothing on the primary freq since something has to give.

Click to expand...

That has always been the case with the "dual-watch" radios. The only way of having two frequencies truly monitored full-time is to have two R/T units, i.e., two radios.

Just to clarify though, the intercom does NOT do this? If something comes in over the primary, the backseat pax does NOT drop out mid sentance for radio priority??

Click to expand...

I'm with Bob here. I've never heard of a radio which will automatically mute a cockpit intercom when it is receiving a transmission (nor a cockpit intercom which would allow this). This would be fraught with danger, for example, in a tandem training aircraft. However there are stand-alone intercom systems where the passengers can be deliberately isolated from the pilot via a switch so they can chat among themselves. These are common.

Sure, listening to ATC is important. But screaming that you have the airplane as student Blogs accidentally puts full pro-spin rudder in during his spin recovery is more important than ATC.

Intercom quality - Good enough or separate intercom?

What is the quality of the intercom like? In a recent discussion with SteinAir they suggested I get a separate intercom and not rely and the intercom on the GNC 255. Does anyone have any experiences they like to share?

Thanks

Rogier