VX8r Antenna, APRS, GPS questions

[hfink]

1. Best antenna?
I noticed people touting the diamond srh320a are there any other antenna suggestions? If you get an antenna meant for just dual or a single range is it going to have a significantly higher gain? any good sites for handheld antennas?

2. Has anyone transmitted APRS in the GMRS range to see if it works with the Garmin Rino?
I have friends/family with Garmin Rino's they can transmit APRS messages in the FRS/GMRS band ex. Garmin channel 1 is 462.5625

3. GPS -> the FGPS-2 is a 12 channel GPS, but...
Does anyone know if it is DGPS or WAAS capable?
Has anyone opened one up to take a look at what it looks like inside? if so please post photos...

Or have you tried to power it without the handheld and hook up some leads to see the raw NMEA sentences it is transmitting?

I'd like to be able to know the current position estimated accuracy (based on # of satellites) reception but don't see it as something it will show from the manual (page 76) has anyone found it to be shown anywhere?

Lastly it looks to only have accuracy reporting up to a hundredth of a nautical mile (.320 or .330) no thousandths place (.321). Anyone find it doing thousandths? I ask this because there is a big difference between hundreths and thousandths... for geocaching etc. hundreths gives you ~60 ft accuracy and thousandths gives you ~6ft accuracy (i know there is still error but at least you are starting from something an order of magnitude better!)

I have good reasons for all of these questions.. but don't want to bore you with the specifics. I am very much going to buy one soon, but just don't know if I want to even bother with the GPS it comes with and instead work on a mod to attach a more accurate external GPS.

 

[ke7vvt]

Good questions hfink. Your post deserves a new thread.

 

[Moleculo]

Best Antenna - Generally bigger is better. The srh320a is recommended often because it handles 3 of the 4 bands that the VX8 can transmit on. However, there are other single or dual band antennas that are larger that will outperform it. You can look at Comet, Diamond, or Maldol for starters and just compare their overall length and gain specs.

APRS on GMRS - the VX8 doesn't care what frequency you have VFOB on...it will transmit the APRS data.

GPS - I haven't tried to hook up the GPS to anything else, but it would be interesting to have those questions answered. As far as accuracy goes - the screen of the radio does tell you how many satellites it is picking up, but I don't see anywhere where it tells you the accuracy.

Here's a sample location that I got off of one of my transmissions. It looks like it does thousands to me:

-117.992600, 34.159333

 

[ke7vvt]

1. I like universal-radio.com because it is very simple. It would be nice to have a little bit more info next to each of the items in the online catalog (price for starters) Amateur HT Antennas

But if you open up a new browser window you can create a tab explosion with every antenna and just start picking them off one by one.

Look for the gain, length, and style of antenna. More bands = less gain for all bands, longer antenna = more gain, style = floppy, stiff, connector style. Gain = good, but other than that I don't know what it is or how to calculate it.

I just looked at a few antenna's on UR, the gain is only showed for some. Is there a way to calculate gain from the "amount of wavelength" the antenna is?

And for comparison, I tried to find info on the stock antenna in the user manual and found nothing.

2. I will look into rhino and aprs this weekend to and see how it works.

3. When I get back down in town tomorrow I'll transmit out a few aprs packets and post a link from aprs.fi and we can see how close it gets to where I was standing.

 

[hfink]

Thanks everybody, based on some of the posts I have a unit and GPS on order, so within a few weeks here I'll get all the sentences it outputs posted as well as the pinouts and see what does what as far as the GPS and NMEA go... -Hfink
On a side note, I plan to also use it to listen in on the Blue Angels air show coming up in Seattle next weekend I think my brother and nephews will love it

 

[TMI]

I've been using a Diamond SRH940 antenna. It's long, but gets me into the 6M band somewhat (not well, but better than the duckie). It it noticeably more sensitive on 2 meters.

However, it is a royal pain to carry. I'll probably get a shorter antenna for carrying around for 2M/70cm use.

At home on the desk, the VX8R is connected to a J-pole hanging in the corner of the room, and that is very noticeably better than the SRH940 on 2 meters and 70 centimeters.

 

[hfink]

Moleculo posted GPS of: -117.992600, 34.159333 I gather from the .xx2600 and .xx9333 -- the 00 and 3's make me feel pretty sure the unit is doing some rounding off even if it is displaying that many digits (as that would be .3 ft accuracy otherwise!)

That being said if you put: 117.9926 W , 34.1593 N into google maps it was good enough to put you within 12 feet of his front door of his house. -not sure exactly where he was when he wrote that down though.

I am guessing right now (will verify soon) it appears that it is probably outputting degrees, minutes-decimal to the thousandths of a minute. (moleculo's is currently formatted in the settings to display degrees-decimal.. and i think that is where it is rounding from) so the accuracy is at: 48'' 20.321' it will be in line with the industry norm for handhelds -that is what I meant by thousandths place (my bad for lack of explanation) putting it with a maximum 6 ft accuracy digit wise (1/1000 of a nautical mile)

In conclusion:
Since these GPS units are probably quite new, and thus contain some of the newer manufacturers GPS chipsets, we are probably dealing with a 12 channel GPS that is fully capable of both the fast and slow WAAS corrections. In my experience with other handheld units on for longer than 10 minutes coupled with a good clear horizon you should normally see accuracies between 6-12ft.. depending on satellite geometry, your proximity to the closest WAAS ground station, and state of the ionosphere, etc. If you are outside of the WAAS area.. then you'll be down in the 20-50 ft zone.

--in any case i'll know more soon enough when I get mine

 

[w3CUM]

Just speaking as to the accuracy of the GPS in regards to WAAS or not. I use a Delorme PN-20 and when I hat both sitting outside in a field full view of the sky they both read EXACTLY the same. I have done this a few times and am always pretty impressed.

Has anyone ever tried to see if the Rhino radio's can see the 8r or if the 8 can see the rhino's when they use it on FRS or GMRS?

 

[KD8LWX]

Has anyone ever tried to see if the Rhino radio's can see the 8r or if the 8 can see the rhino's when they use it on FRS or GMRS?

As I dig into APRS, I do not see FRS or GMRS mentioned. So I would think that it doesn't work, but I would love to have someone do the test.

This goes to my question. If I have a VX8r and another VX8r, both with GPS, both with APRS setup, not around a digital repeater, can they see each other? (Or if someone has access to 2, could they set them up on a different then normal freq and tell me if they see each other?

 

[kc0zmx]

This goes to my question. If I have a VX8r and another VX8r, both with GPS, both with APRS setup, not around a digital repeater, can they see each other? (Or if someone has access to 2, could they set them up on a different then normal freq and tell me if they see each other?

They will see each other just fine! Having a digipeater around will just increase your range and chance of an igate picking up your packets. You could use any frequency, but 144.39 is the standard in the US.