Author Topic: new purchase 62s or 64  (Read 4574 times)

mabel

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new purchase 62s or 64
« on: October 08, 2014, 11:33:03 PM »
I am looking to upgrade my very old etrex (not the H version).

I have not kept up with the technology in recent years.

The short list is a etex30,  GPSmap 62s, GPSmap 64

I am not bothered by all the Bluetooth connectivity stuff, the 
electronic compass would be nice but not worth more than 10 or 20 bucks (I 
have a perfectly good real compass and a map). the barometer is not of much interest to me either.

All have high sensitivity antenna, are they all equally sensitive?
(I assume the quad helix part is more to do with signal orientation rather  than sensitivity)!!!

The 64 has glosnass (sounds good), does this improves positional accuracy at all!!!   
or is the only real benefit,  the faster lock on times and more 
satellites to get a lock on?

Basically would I stand a better chance of finding a way-marked Stile a 
km away with the 64 compared to the other two units?

I assume all three of the newer units will be less likely to lose 
signal than my old etrex.


I am basically only going to use it in the UK.

Are there any draw backs to buying a package deal, one with maps on a card compared to buying them separate? There is a price advantage of course.

Are the bundled maps the same as the separate maps (same detail, accuracy etc.)?


I only use it when I going out on walks with my wife, we will not be attempting to follow 42 commando anywhere :-)

I would like, I think - open to advice, to have the 1:50k set of maps and selected 1:25k maps for the area we are holidaying in loaded into the device.

ideally the whole country at 1:25k would be perfect - but expensive.

I 'think' I read somewhere that if I buy the map on a card I can't transfer it to the device so I will be limited in what I can load onto the device.

but if I buy the map separate as a download  can I load it onto a 16 Gig memory card along with other maps.

ideally i would like the full 1:50k of the UK (i see a package deal is available) and selected 1:25k for the area i am visiting all loaded simultaneously.

i don't really want to carry and change memory cards in the field.

how much memory does a 1:25k of a national park take up; how many maps can i get into the 16 GB card basically

Thanks for any advice/help


Angle of Repose

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Re: new purchase 62s or 64
« Reply #1 on: October 09, 2014, 12:33:42 PM »
I am in the market for a new Garmin GPS as well, and have been looking at the 62S and 64 as well.
From what I gather from this chart: http://www.gpscentral.ca/products/garmin/gpsmap62seriescomparison.html
the major differences between the two are increased internal memory, waypoint storage, and a few extra hours of battery life.
That and a good price difference. I plan on getting the 62s and installing my own free custom maps.
Can't comment on the GLONASS as I haven't owned a GPS with that feature.

Here is another chart to compare features: http://gpstracklog.com/compare/garmin-handheld-gps-comparison-chart

Garmin 62S review: http://freegeographytools.com/2011/still-looking-for-a-good-fieldwork-handheld-gps-a-review-of-the-garmin-62s-part-i
« Last Edit: October 09, 2014, 12:35:43 PM by Angle of Repose »
"You can't get there from here"

mabel

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Re: new purchase 62s or 64
« Reply #2 on: October 10, 2014, 12:29:23 AM »
yes - that's were i was leading - in a round-about-way.

 maybe the 62s is better value, as there may be some end-of-stock deals about.

i was considerig the 64 as it was newer, but only if glosnas was actually going to show some benefit.

however, as you point out, the  increased internal memory, waypoint storage, are nice.

but i assume with the 16GB card in the 62 then i should have enought memory for the full 1:50k and selected 1:25k maps

hay-ho
« Last Edit: October 10, 2014, 12:31:05 AM by mabel »

captain paranoia

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Re: new purchase 62s or 64
« Reply #3 on: October 10, 2014, 01:26:24 PM »
> Basically would I stand a better chance of finding a way-marked Stile a km away with the 64 compared to the other two units?

Realistically, the precision with which rights of way and tracks are marked on a map, even a 1:25k map, is far poorer than the accuracy you can usually expect with any GPS receiver using the Coarse Acquisition (C/A or civilian) service, barring receiver perturbations.  So finding that stile (not usually marked on maps...) will still need you to find the physical stile.  Which can sometimes be a challenge in overgrown hedgerows...

A track depicted as 1mm wide on a map would be 25m wide on the ground using a 1:25k  map, and 50m wide on a 1:50k map.

Receiver sensitivity is a double-edged sword.  On the one hand, it allows you to pick up weak signals.  On the other hand, it allows you to pick up weak signals.  Weak signals can be caused by attenuation of the line-of-sight signal (e.g by tree cover), or by reflection of the line-of-sight signal from surrounding objects (e.g. tree trunks and branches).  So, whilst a higher sensitivity receiver might continue to track under thick tree canopy, you should expect the fix to be degraded due to multipath and reflections.

The more satellites you can see, the better your solution ought to be, with a law of diminishing returns.  So, being able to see GLONASS should give your a marginally improved fix, but it might only give you 3m average error as opposed to 5m (for example).  It is unlikely to improve your Time To First Fix (from a cold start), since the two systems are separate, and you will still need to acquire the ephemerides for both constellations before the receiver can start calculating fixes.  A receiver with Predictive Ephemeris capability should allow you to increase the lifetime of the stored ephemerides, and so you should usually only need a warm start, admittedly, with some degradation in position until the true ephemerides can be received.

The antenna type is often determined by the physical design of the receiver box, rather than performance.  For a dedicated GPS receiver (as opposed to a phone), the chances are that the antenna performance will be good enough, and not really worth you bothering about.  It's useful to know where the antenna this 'up' is, though, so you can position the receiver so that it gets the best view of the sky (rather than having half of its beam profile pointing at the ground).

For mapping; if you want to find stiles, you'll need a map depicting field boundaries.  So, for the UK, that means 1:25k OS maps, as 1:50k maps don't depict field boundaries.

I know your stile comment was just an example of the accuracy you were hoping for, but it serves as a useful way of thinking around what your requirements are ;-)

For the mapping side, I'm afraid I can't help, as I don't have experience of commercial mapping receivers; I use a GPS PDA with full UK 1:50k and 1:25k mapping that fits on a 16GB card, and a Hudl running OruxMaps that will cache or download OS tiles from Bing (no longer available due to legal pressure from the OS).  I also have a full set of UK mapping for Locus on the Hudl, but that takes just under 30GB.  I prefer OruxMaps for user experience.

What might also be interesting to you is the navigation guidance the receiver gives you; again, I can't help here, as my GPS PDA merely plots my position on the map, and route following is up to me.

Can routes be prepared on the device, and, if so, how easy is it to do that?
How easy is it to transfer routes & logs to and from a computer?
How easy is it to manage routes on the device?
Does it offer folders to allow routes to be organised?
Does it allow enough characters in waypoint names for them to be usable?
Does it re-name your carefully named waypoints in routes?
How well does it cope with routes that double-back on themselves (for instance, when automatically advancing to the next waypoint)?
Can it distinguish between waypoints and route points (this can be a solution to the above; a genuine waypoint at the far point of a double-back route, with routepoints following the meander to and from that waypoint).  I'm not even sure if GPX files understand this distinction, although one might choose to write a GPX file as a set of waypoints, between which are route or track segments.

mabel

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Re: new purchase 62s or 64
« Reply #4 on: October 10, 2014, 04:40:00 PM »
thank you for the comprehensive reply.

that gives me something to digest.

the stile example was basically referring to routs i download that someone has previously marked on their unit.

but thinking about it, the accuracy of his fix may be off by 5 m to the north say and if mine is off to the south then i may still not find it.

i take your point about weak signals.

thanks again

boogyman

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Re: new purchase 62s or 64
« Reply #5 on: October 10, 2014, 07:23:46 PM »
I've used an eTrex HCx for over five years, and then bought an eTrex 20 (a good 6 months ago). The latter has a receiver for GPS and GLONASS. And yes, that makes a big difference. The biggest advantage in my opinion is not so much the increase in accuracy, but rather the increase in the "statistical probability" that you have a decent coverage at any given moment in time (you could call that an increase in accuracy too, but I hope you understand what I mean). If I had to buy again tomorrow, it would certainly NOT be a GPS only receiver.

Hugh Westacott

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Re: new purchase 62s or 64
« Reply #6 on: October 10, 2014, 11:25:40 PM »
CP wrote:

<For mapping; if you want to find stiles, you'll need a map depicting field boundaries.  So, for the UK, that means 1:25k OS maps, as 1:50k maps don't depict field boundaries.>

At the risk of being considered a pedant I should point out that most authors of books on navigation seem to believe that the Ordnance Survey maps the UK at 1:25,000 and 1:50,000. It does not! The Ordnance Survey maps Great Britain (i.e. England, Wales and Scotland) at !:25,000 and Great Britain and the Isle of Man at 1:50,000.

The Ordnance Survey of Northern Ireland (OSNI) maps the Province at 1:50,000 and selected areas at 1:25,000.

The Ordnance Survey of Ireland maps the Republic at 1:50,000 and selected areas at 1:25,000.

Hugh

captain paranoia

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Re: new purchase 62s or 64
« Reply #7 on: October 12, 2014, 11:11:55 PM »
Sorry, Hugh; I was very sloppy with the UK/GB terminology...

Hugh Westacott

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Re: new purchase 62s or 64
« Reply #8 on: October 13, 2014, 08:49:37 AM »
<I was very sloppy with the UK/GB terminology...>

it's easily done, CP, and it's difficult to correct especially when so many books containing chapters on navigation for walkers and climbers make the same error. On page 7 of Carlo Forte's Navigation in the Mountains; the Definitive Guide for Hill Walkers, Mountaineers and Leaders, which is the official navigation book for all Mountain Training Schemes, the following statements appear:

In the British isles  the main providers of suitable maps for walkers are the Ordnance Survey (OS) and Harveys
This implies that the OS publishes maps of the UK, the (British) Crown Dependencies of the Channel Isles (Guernsey and Jersey) and the Isle of Man, as well as the Republic of Ireland. As stated in my earlier post, the OS is only responsible for mapping Great Britain (England, Scotland & Wales) although it also maps the Crown Dependency of the Isle of Man but only at 1:50,000. The Republic of Ireland, Northern Ireland, Guernsy, Jersey are each responsible for their own mapping and the isle of Man publishes its own 1:25,000 map.

The OS maps of the UK are now fully digitised...

Ordnance Survey (OS) is the national mapping agency for the UK

OS is widely regarded as the most systematic and thorough mapping agency in the world, detailing every corner of the UK...

On page 8 appears the statement In the UK both OS and Harvey maps provide similar levels of detail...

Page 11 In the UK Ordnance Survey maps generally use a 10-metre interval, although lowland regions have 5 metre contours on 1:25,000 maps...

The term ‘generally’ is misleading. Of the 402 1:25,000 Explorer maps, 333 have 5-metre contour intervals and only 69 have 10-metre contour intervals. All 204 1:50,000 Landrangers have 10-metre contour intervals so when the two series are combined there are 333 maps with 5-metre contour intervals and only 273 maps with 10-metre contour intervals. (This information was supplied to me by the Ordnance Survey.)

According to the Acknowledgements, the text was read by umpteen experts, including the staff of Plas y Brenin, but none of them seemed have noticed the errors. What bothers me is that this is the navigation manual used on all Mountain Leader training schemes so goodness knows how many otherwise well-qualified hillwalkers and mountaineers have been fed incorrect information. The chapters on navigation in the companion volume Hillwalking contain similar errors.

Hugh

John-C

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Re: new purchase 62s or 64
« Reply #9 on: October 20, 2014, 09:12:02 AM »
Mabel,

ref card vs download of 1:50,000...

Yes, I fell into the "deal" trap a few years ago. If its supplied on a card, you will need to have the card inserted to use it hence 1:25000 would need to go on the internal storage (unless you are happy to use the spare capacity on the card at risk of messing it up!).

Downloading it means its constrained to your device, but gives you the ability to use a bigger card.

I tried all sorts of things to get over this, and even asked Garmin if I could pay for the 1:50,000 to be put onto a larger card, or part ex the card for downloadable/exchange for a reasonable discount etc, but there was no way they would budge - in their eyes if you have a map supplied on a card, & want to change to downloadable, tough, you need to buy the download!

..............Alternatively, you could consider using a product from a company who cares.


mabel

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Re: new purchase 62s or 64
« Reply #10 on: October 28, 2014, 10:27:00 PM »
Thank you for that information.

i will have to reconsider my way forward.

thanks again

ianj37

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Re: new purchase 62s or 64
« Reply #11 on: November 02, 2014, 05:09:26 PM »
 As a follow-on to John-C's points.

I bought a 62s earlier this year with the 1:50k GB map on a card and, like you, intended to download specific areas of interest as 1:25k from Garmin Birds-eye mapping. The problem I have found is that they don't keep the Birds-eye mapping up to date. I know this because I know one area of the Peak District particularly well and on my 2011 1:25k OS map there are 2 paths, which I know physically exist, that aren't on the Garmin 1:25k download (and I checked again today). At the time I asked Garmin when the maps would be updated and their response was that they didn't know when or even if they would be updated. This fits in, I suspect, with John's comments about caring about customers.

Good luck with your purchase!

Ian