GPS module for a clock

I'm having difficulty finding reasonably priced GPS modules which actually work. I intend these to work in a clock. I've bought 4 "Neo" like modules recently from 2 different Aliexpress retailers. Out of the 4 modules, only one works.

Of course I know all that stuff about you get what you pay for etc. but I've almost always got usable electronic components in the past even if a clone/copy etc. and am prepared to accept a few quality issues (and long delivery times) for a reasonable price. But I find this high failure rate for these devices somewhat uncharacteristic.

Having said that, I invoked the Aliexpress dispute procedure for the first batch of 2 modules from the first retailer, both of which were completely dead, and got a more or less instant refund.

For the one failed item of two I received from the second retailer I'll probably do the same. The failure here is somewhat more subtle. I get a constant stream of NMEA messages but packed with default settings because it never sees a satellite. I have now discovered this due to the module not producing any power for the active antenna. When an active antenna is connected via a DC blocking capacitor and the antenna separately powered, it does show some sign of life.

But this is just a nuisance. Part of the problem is the Aliexpress delivery confirmation system. When you confirm the delivery you are put under pressure to simultaneously evaluate the whole thing, making the evaluations somewhat meaningless and useless for supporting the decision to buy a specific item. For example, many evaluations will be something like this:

(*****) five stars. Quick delivery, well packed, looks great. Not tested yet.

In fact, the evaluation I left for the first retailer above looked similar. There will be many purchasers who simply leave no message but the default 5 stars. Now I have been scouring Aliexpress for "Neo-like" GSM modules which have a number of useable (and plausible) reviews. I find very little, even for those items which claim large numbers of sales.

Had similar problems with the so called Neo6 GPSs myself, and quite often others report issues here.

One GPS that does work well is the Quectel L80, small and not expensive. Never had problems with those I have bought on Aliexpress.

One issue was noted with the Quectel L70, so may impact the L80 as well, they stop working at an altitude of 10,000m, when they should not when set to balloon mode. A genuine L70, bought from a trusted source in the UK, did work correctly at 10,000m+.

I do sell bare PCB breakout boards for them, you can add components to power down the GPS etc.

Don't forget that the clock will need a view of the sky. The only place in my house that I can get a fix is under a skylight.

I got these, dunno what you consider inexpensive…

I have had zero trouble with them and they work way better than I thought, maybe there’s a GPS satellite right over my house or something. :expressionless:

Compared to the old days of SA, finicky reception and $$$ pricey gear (and nothing like the module above), I was happy to shell out and never look back.

I am just using the patch antenna on the module but it has a connector you could use for a remote antenna or at least one over in the window if you needed.

a7

Well I see ppl want to spend like 1/10 of $30… I do not understand how all the stuff we buy can possibly be so cheap.

I too am willing to eat a few things that go wrong, and I can try to save money like the best. But at a certain point for some kindsa things you gotta ask yourself what your time is worth.

a7

1 Like

Thanks for the feedback. The price information is this:

"Neo-6" from retailer 1 < $3.00 Two modules, both modules completely dead.
"Neo-M8N" from retailer 2 $7.99 No power supplied to active antenna.
"Neo-6" from retailer 2 $4.70 Works perfectly.

Of course, retailers like Adafruit are very reliable. However, up until now, with Aliexpress/Ebay, I have almost always received something at least usable. These GPS modules are a big exception. With retailers who specialize in electronic components, there is an expectation that they can at least test their products. If the retailer is also selling womens' underwear and garden tools etc., of course there are no such expectations.

A clock is not very demanding. The only working module I have picked up a time within a couple of minutes, even with the module on my desk. I think for that only one satellite is required. A full position fix (2D/3D) is more demanding

Sometimes they can get things to your door way faster. :expressionless:

Adafruit are probably easier to deal with in the case where one is not satisfied with a product.

a7

That is not a failure, unless the module is specified as supplying power.

Interesting point of view.

The module does specify that an active antenna is required. It has, however also an IPX socket on the module. Most of the common antennas, the ceramic ones, are active. That is these have a single transistor amplifier. I have not seen one of these which is externally powered. In fact, I have seen very few SMA antennas which are externally powered.
The GPS module with the "Neo 6" does supply antenna power but not explicitly state that.

Here is an advert for the "Neo M8N" which is referring to the same module I purchased but the retailer is NOT the one I used. Neo 6m Neo 7m Double Sided Gps Mini Module Neo m8n Satellite Positioning Microcontroller Scm Mcu Development Board For Arduino|Integrated Circuits| - AliExpress
Schematics for the Neo-M8N show a pin labelled Vcc-RF for powering the antenna.

Well, I succeeded in "fixing" the main "Neo M8N" GPS module by delivering 3.3 volts at the point where the "Neo" module's Vcc-RF pin would have delivered it and it appears to work. I checked previously with a meter that, with no antenna connected, there was no current flowing between the points I bridged. It is still a mystery, however, what has gone wrong to make this necessary.

The results from the ublox u-center. The GPS module was just on my desk :

and the "fix". Note the bridge between C1 and R4 :

I've been using a module with a passive on-board antenna and an SMA socket.

From here:
link to supplier's page

photo:

The supplier advises:
"Please note: When connecting an external antenna the C2 capacitor on the module needs to be removed. If the internal and external antennas are used together they will interfere with each other, affecting positioning."

Does that have any bearing at all on the situation with your board?

1 Like

OK. Thanks. I looked around and found this for what looks like your board: KS0319 keyestudio GPS Module - Keyestudio Wiki
In your case, the integrated "Patch" antenna is passive and there is an external RF amplifier (Max2659). The SMA socket is power fed from the Vcc-RF pin on the neo-7 module. The capacitor C2 simply isolates any RF signal derived from the patch antenna which, as the documentation points out, could cause a conflict with a signal via the SMA socket.

In the case of my module, any possible conflict is resolved by the user not installing simultaneously both an IPX antenna and an SMA antenna.
Any antenna (IPX or SMA connected) has to be active because there is no equivalent of the Max2659 RF amplifier as on your board.
The pin marked Vcc-RF on my "neo-M8n" simply does not produce any power, hence my "work around". I'm guessing that there is some mismatch between the "neo" module, the firmware that has been loaded into it and the board it has been soldered to.

Having modified it, the performance is quite good even indoors with the IPX patch antenna (my house is of wood construction). However, there is now no protection against any possible short circuit at the antenna.

You'll have noticed that there is a considerable price difference between the modules, I guess for a good reason.