Another Just sorry he was in a Mooney - can't fly IFR because iPad died

[Pinecone]

On 8/3/2024 at 1:51 PM, hubcap said:

I get that, and did not want to imply it couldn’t be done. However, using my IPad for GPS navigation in IMC is below my personal minimums. I will drive before I intentionally put myself in that situation.

It would be a bit more challenging.  But the only big issue is we use GPS as pseudo DME, so would not have that part.  And DME makes VOR nav so much better.

[EricJ]

1 hour ago, Pinecone said:

Hmm, I said that earlier.

I think that Garmin could develop and LRU for DME and some software changes in the GTN series to do VOR/DME and DME/DME navigation as a fall back/back up to GPS.

I've been saying it for years.    Several years ago somebody in the UK had achieved basic functionality with an RPi and could show location on a map just from VOR inputs, but I never tried using that particular app and it doesn't look like it got a lot of use.  I initially lost interest in doing it because that guy had done it, but it doesn't look like that solution went anywhere.  Adding DME would improve accuracy, but also add a lot of cost and complexity and would require FCC certification since it transmits.
 

[Pinecone]

I was just thinking the VOR/VOR nav could be done with software for something like a GTN navigator.  VOR receiver is already there, just need to switch back and forth between two and process the info.

And, yes, adding DME would be a bit more, but should not be a huge deal or cost.  And it adds a LOT of capability with VOR/DME and DME/DME and even DME/DME/DME nav.

[toto]

2 minutes ago, Pinecone said:

I was just thinking the VOR/VOR nav could be done with software for something like a GTN navigator.  VOR receiver is already there, just need to switch back and forth between two and process the info.

And, yes, adding DME would be a bit more, but should not be a huge deal or cost.  And it adds a LOT of capability with VOR/DME and DME/DME and even DME/DME/DME nav.

It could absolutely be done with software, and above a certain altitude there's no particular need for DME.  DME becomes critical if you only have one VOR in range, for obvious reasons

 

[Pinecone]

It is just that they are increasing DME coverage or at least leaving the DME working when the VOR is taken out of service.   This is because a lot of airliners use DME/DME/DME/INS for nav, so they need the DMEs.

And a DME is a small foot print install without the issues of VOR (shifting mag variation).

[201Mooniac]

1 hour ago, Pinecone said:

I was just thinking the VOR/VOR nav could be done with software for something like a GTN navigator.  VOR receiver is already there, just need to switch back and forth between two and process the info.

I'm sure if you had two GTNs connected over HSDB, then VOR/VOR area nav would be a simple software solution without even having to worry about switching the VOR frequencies and dealing with smoothing during transition settling.

[EricJ]

1 hour ago, Pinecone said:

I was just thinking the VOR/VOR nav could be done with software for something like a GTN navigator.  VOR receiver is already there, just need to switch back and forth between two and process the info.

And, yes, adding DME would be a bit more, but should not be a huge deal or cost.  And it adds a LOT of capability with VOR/DME and DME/DME and even DME/DME/DME nav.

An RTL-SDR USB tuner, like could be used with a Raspberry Pi, can digitize the entire VOR spectrum at one time, so that you can simultaneously digitally tune as many VORs as you can find in range.    Whether or not you can do that in software in a GPS depends on a lot of things, including whether the tuner has enough bandwidth or not and whether there's enough processing power available to do the job.   If the tuner is narrow band and can only tune one VOR at time, then it'd be a bit slower and clunkier, but could potentially still work reasonably depending on other things.

I suspect only the most modern GPSs may have wideband digital tuners, and I don't know which do or don't.   Because of some work I've done with the Avidynes I think they *might*, but I'm not sure.    What I do know is that it's not an issue with an RTL-SDR and an RPi, so for a few hundred bucks (at the most) you could have the capability connected to your tablet via WiFi.

 

[Pinecone]

On 8/6/2024 at 10:55 AM, 201Mooniac said:

I'm sure if you had two GTNs connected over HSDB, then VOR/VOR area nav would be a simple software solution without even having to worry about switching the VOR frequencies and dealing with smoothing during transition settling.

Good point