EEVblog #721 - Globalstar Satellite Phone Teardown

[SeanB]

I actually do have a worldspace radio in a cupboard. Wonder if i should do a destructive teardown on the remote antenna puck it has.

[German_EE]

Ages ago I asked Shahriar to do a talk on Signal Path about RF Voodoo and all the various PCB based filters that can be seen. Maybe we will see it someday.

[G7PSK]

I have always wondered with those RF assemblies, do they design the PCB then order shielding cans to fit or do they purchase standard size shielding cans then design the PCB sections to fit inside them?

You design the PCB to fit in the area to form a rectangle, then you go and have the dies made for the shields, and they get pressed out of tinned sheet steel. If you are only doing a few you can use premade shields, but there you are constrained by the shield. The roll your own allows you to have custom leadout slots in the shield for traces, and to have custom sizes and also have the option of having those shorting straps across the shield, or to have custom contacts to allow a press fit cooling clip for power devices.

Off the shelf is cheap in low quantity, but the custom parts allow you to have smaller assemblies. The die costs though are pretty high, you are looking at $10k per set or so for each unit, comprising of a set of press plates, cutting dies and punches that form all the edges and holes in the unit, along with the clips to hold it together in a single set.

Custom made shielding cans can be made quite cheaply with tools such Amada turret punch press which use standard size punches to cut out various shapes.

http://www.amada.co.uk/product/details/11/ae-nt-series

[SeanB]

I think the punch press is going to be a little more than $10k though. Custom is cheap in lots up to 10 or so where you use a simple metal worker in a engineering shop to hand make them. Cheap at a half million, where you can amortise the cost of the machine and presses over a large number of units, and then you can sell the excess capacity as a 'standard' size. In between you buy standard or build in the cost of the machinery and dies, or have a die set made for an external press contractor.

[Sasja]

question: what are those parts that look like crystal packages and have traces running underneath?

[mxmarek]

Shouldn't You hold the antenna horizontally to get maximum signal gain up the sky ?

[kotaKat]

So, figured I'd step in. I've owned a GSP1600 and currently own an Iridium/Motorola 9505A and a Thrane&Thrane Explorer 300 BGAN terminal for Inmarsat. Both a couple good deals on eBay

A few notes:
- The orange tip? Like fake guns, they colored the tip of the erectile antenna orange to avoid people thinking you've got a gun.
- If it's not activated, it'll register and unregister repeatedly with the Globalstar network. No test calls.
- If you have CDMA (highly unlikely) you can register the cellular side. In the States for the longest time a Verizon MVNO did allow you to activate them on cellular, long past the E911 mandate. Of course, it was ONLY the cell side, so you still had two bills!
- The network was quite shite for a long bit of time due to satellite failures and pesky end-of-lifecycle issues. They had service down to $35 US a month for "unlimited" service at one point, mind you - but you had to use a "call times" tool to see that you can only make a 5 minute phone call for maybe two windows in the hour.
- The multipin connector on a lot of these terminals (not just Globalstar's) are full on docking stations for fixed stations. As an example, I could slot my Iridium into a dock that gives me RJ11 phoneline connectors, serial access, an external antenna, and lets me run it off mains power.
- Native data rates are 9600 baud on Globalstar and 2400 baud on Iridium. Normally, TCP "acceleration" is provided to give you compressed data around 10-20k speed.

BTW -- Globalstar will sell you their latest and greatest SatFi (satellite data/voice terminal for smartphones) for $1k US -- and all they give you is a Gumstix Overo, third-party WiFi module, and an off-the-shelf old stock Globalstar integrator's module - tied together with some dodgy rebranded OSS.

[hikariuk]

Weird that there's very little coverage over the sea, that most voice coverage is concentrated where regular cellphone coverage is good.

I would have thought a major market for these 'phones would be people with boats.

Most ships use Inmarsat, ime.

[DanielS]

Shouldn't You hold the antenna horizontally to get maximum signal gain up the sky ?

That depends on antenna polarization and in this case, I would guess it uses circular and gets the highest gain by pointing up.

[Rory]

Quadrifilar helix.

[EvilGeniusSkis]

Finally, when my first daughter was born, I proposed to my wife to name her Ethyl.  The second girl would be Methyl.  My wife didn't think this was a good idea.

would the third girl have been named Keytone?

[kotaKat]

Shouldn't You hold the antenna horizontally to get maximum signal gain up the sky ?

That depends on antenna polarization and in this case, I would guess it uses circular and gets the highest gain by pointing up.

Correct. That's also why they have the angled "detents" so that it stays pointing up when you hold it to your head.

[mxmarek]

Quadrifilar helix is just pure black magic designed by demons

[Stonent]

Quadrifilar helix is just pure black magic designed by demons

[N2IXK]

Well isn't that Speeeecial?

[rollatorwieltje]

Ah, the 386EX. I have a board the size of a Raspberry Pi with one on it, dated around 2002. Power consumption of that board was about 300mA at around 33MHz. Quite a surprise to see one in a phone.

[edy]

Dave, did I miss it or did we not review the mechanics of that "erecting" antenna? Was there a gear that drew out the antenna as it swiveled, or a pulley cable system? The mechanical side would have been interesting too although the electronics takes priority of course. Still, a bit of engineering marvel. Perhaps a quick 2 minute follow-up in your next video would help.