2014-09-17

Naked hardware #17: PCTV DVB-S2 Stick (461e)

PCTV DVB-S2 Stick (461e) teardown

PCTV DVB-S2 Stick (461e)
Outwardly, that satellite receiver is just similar than its predecessor, having even same name, but different model number 460e. Also feature set is same - DVB-S/S2 USB receiver with remote controller. Without common interface (CI), it cannot be used for receiving encrypted channels, but free-to-air (FTA) content only.

Only differences between old and new version could be found from the device internals, where DTV chipset is changed to totally different one. Old model uses NXP TDA10071 & Conexant CX24118 demod & tuner combo, whilst that new one is build upon Montage M88DS3103 & Montage M88TS2022. 461e appeared to marked circa one year ago (around September 2013) and replaced old 460e quickly. 461e USB ID is 2013:0258, whilst 460e uses ID 2013:024f.

Initial Linux driver went into Kernel 3.14. Currently that device is one of the rare USB satellite receivers, having both good availability and drivers in mainline kernel.

Unfortunately I don't have a retail package, but only the stick itself. Retail package should include additionally remote controller and USB cable - which are those same coming with almost every PCTV Systems USB receiver. So lets forget all that extra stuff and take a look to device internals! 

Key components:
Empia EM28178
Montage M88DS3103
Montage M88TS2022
Allegro A8293

General hardware design

Device is build on single PCB, having USB connector on other end and antenna connector on the another. There is surprisingly large amount of components, assembled to both PCB sides rather compactly. I wonder how there could be that much extra components needed for connecting few chips together... PCB is also rather big if you compare to most DVB-T USB devices, but DVB-S/S2 receivers tends to be  bigger than DVB-T receivers always. I think it could be still even smallest USB satellite receiver currently.

External 12V power supply is needed, as always for USB satellite receiver, feeding power to LNB. Similar (same?) power supply was used for old 460e too.

PCB upper side

PCTV DVB-S2 Stick (461e)
All important chips are assembled that side of the PCB. Chips counted from antenna connector are M88TS2022 (RF tuner), M88DS3103 (demodulator), EM28178 (USB-bridge). USB-bridge is partly under the IR receiver component. A8293 LNB power supply is small chip near external power supply connector and big component marked WE 330 (power inductor).

Montage M88TS2022

Montage M88TS2022
M88TS2022 is satellite tuner. It receives LNB IF frequency and drops it to the baseband aka Zero-IF. That tuner is successor of the M88TS2020. Both M88TS2022 and M88TS2020 are quite similar. M88TS2020 was used mostly with M88DS3000 demodulator whilst M88TS2022 is usually seen as a pair with M88DS3103 demodulator.

27 MHz clock needed is feed from crystal located another side of the PCB. 

Montage M88DS3103

Montage M88DS3103
DVB-S/S2 satellite TV demodulator. That chip receives radio signal from the tuner (M88TS2022) and decodes it to bit stream, which is then feed over MPEG TS interface to the EM28178 chip. That demodulator needs ~8kB firmware, which is downloaded by the driver. 27 MHz clock is feed from the another side of PCB. There is only one 27MHz crystal on whole device, which means clock is shared between tuner and demod. Clock sharing is nowadays very common as rather costly crystal components could be saved easily.

There is another very similar chip seen on some other PC receivers. That chip is M88DS3002. I suspect it is only earlier revision and differs marginally from the M88DS3103. Even before M88DS3002 there was M88DS3000 DVB-S/S2 demodulator, which is same chipset family, but differs more or  less from M88DS3002/M88DS3103. There is existing Linux driver for old M88DS3000 too. M88DS3000 => M88DS3002 => M88DS3103.

M88DS3103 demodulator in conjunction with M88TS2022 tuner is very common DVB-S/S2 DTV chipset currently. I don't have clear vision how widely it is used for STBs or TVs, but for PC TV market it is in practice the only one chipset used at the moment.

Empia EM28178

Empia EM28178
That chip is DTV USB-bridge, from the rather popular Empia EM28xx family. Its main job is to transfer stream from the demodulator to host computer over USB. It also handles remote controller.

In this picture there is remote controller receiver partly top of the EM28178. It is that quite big three pin component having long legs.

Required 12MHz clock is coming from crystal located another side of the PCB. Also eeprom, needed by bridge, is located another side. EM28178 loads configuration from the eeprom during power-up. That configuration contains USB ID amongst the other things.

Same EM28178 bridge chip was used for PCTV tripleStick (292e) receiver too.

Allegro A8293

Allegro A8293
LNB power supply. LNB needs power in order to work properly. Power is feed over antenna cable and that chip does that job. Voltage is also used to select receiving signal polarity - horizontal or vertical.

Chips is controlled over I2C bus.

That same chip was used for older 460e model too.

PCB bottom side

PCTV DVB-S2 Stick (461e)
Visible parts are, two crystals, eeprom and current limiter chip.

Crystal near antenna is 27MHz and feeds clock for demodulator and tuner. Another crystal, center of PCB, is 12MHz for USB-bridge.

PCB printings:
Redshift
2000000-02 LF
pctv systems

12.000 MHz crystal

Xtal 12.000 MHz
Clock source for Empia EM28178.


27.000 MHz crystal

Xtal 27.000 MHz
Clock source for Montage M88DS3103 & M88TS2022.

Microchip 24LC128

Microchip 24LC128
Eeprom package marking "4LC", Microchip 24LC128, 128Kbit serial eeprom. That chip contains device specific configuration, like USB ID.

Alpha and Omega Semiconductor’s AOZ1360

Alpha and Omega Semiconductor’s AOZ1360
That chip is current limiter. It is located very near external power supply connector and LNB power supply chips, which both are located just opposite side of PCB. I think it is there to protect device for possible LNB power short circuit.

Component is passive and do not need a driver.

Linux driver

Linux driver has been in kernel since 3.14. Device driver consists of 4 chip drivers: em28xx, m88ds3103, m88ts2022 and a8293.

Device needs firmware for M88DS3103 demodulator, which could be downloaded from here.

USB interface

IDLE current drain without a driver: 60 mA



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7 comments:

  1. Are there datasheets for Montage M88DS3103
    Montage M88TS2022 available?

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  2. I know this is a long time after the post but I just recently got one of these due to the driver being in the linux kernel and although it's recognised and firmware is loaded to the device and everything seems good it doesn't actually provide power to the LNB so it doesn't work. However if I plug it into a windows box once the supplied software finds the device it provides power to the LNB and everything works as expected. Is there possibly a new revision of this stick?

    ReplyDelete
    Replies
    1. Which application you used to tune? Could you try w_scan?

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    2. This comment has been removed by the author.

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    3. Sorry I took so long to reply I wanted to test a bunch of stuff to make sure it wasn't just user error.
      As far as I can tell there's no concept of power control for this stick. So if you have a standard LNB it works just fine and you don't even need to plug in the power adapter that is supplied.
      This means however if you wanted to put a sat finder between the stick and your dish for initial setup it won't get powered up. If your LNB requires power for some reason or you have anything inline that takes power (a rotor for instance) the stick seems to fail I guess because not enough power makes it to the LNB. DiSEqC of any sort is impossible because the required power isn't there.
      What is interesting is that under windows there seems to be a similar problem (I did limited testing with this) in that the installable BDA drivers seem to behave the same way in that if I use DVBDream for instance I can't tune if I have a rotor or anything in the way. However if I fire up TVCenter it will tune and I can use positioning controls in DVBDream if I run it at the same time.

      TL;DR
      Running TVCenter under windows produces power from the included PSU
      Every other program/driver seems to ignore the PSU and doesn't switch the voltage through to the coax.
      Will tune successfully with standard LNB if no power requirements on the input from the dish.

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  3. Hi Ian,

    I have discovered the same power issues with this adapter, I use C-BAND so can not test TVCenter, I don't know why PCTV won't offer the option for C-BAND LNB frequency in setup. With DVBViewer I have had success only because you can turn power/on off between switching Transponders. But that doesn't help either really because at some stage the recieved signal becomes unstable. Probably because as you're saying, it doesn't supply the power to the LNB

    Hope they fix this soon, I've asked for a refund, totally disappointing and they don't mention they don't support C-BAND, yet they have cband muxes in their scan configs , no good

    ReplyDelete