Naked hardware #11: unbranded RTL2832U + R820T

RTL2832U + R820T bulk DTV stick teardown

That stick is Realtek RTL2832U reference design with Rafael Micro R820T RF tuner . USB ID is 0bda:2832, which is chipset default reference design ID. Why there is still eeprom?

Linux support has been added since the Kernel 3.10.

unbranded RTL2832U + R820T

unbranded RTL2832U + R820T stick

Key components:

Realtek RTL2832U
Rafael Micro R820T

Hardware internals

RTL2832U + R820T stick PCB

All components are assembled to that side of the PCB. Very standard RTL2832U stuff with nothing extra. Main components from left to right are: power LED, IR-receiver, MCX antenna connector, A7 - BAV99 diode, R820T RF tuner, 28.800 MHz crystal, 24C02 serial eeprom, RTL2832U DVB-T USB interface + demodulator, FS1117 voltage regulator and type A USB connector.

28.800 MHz clock is shared with RTL2832U and R820T - saving one component. BAV99 diode is used for ESD protection. It protects RF tuner possible ESD coming from antenna connector. RTL2832U devices having that RF tuner are very popular currently, especially in SDR usage.

There is not much to explain as I have already teardowned two devices build upon RTL2832U, but having different RF tuner. Look these first:
Naked hardware #6: ezcap USB 2.0 DVB-T Stick
Naked hardware #7: TerraTec Cinergy T Stick Black

R820T RF tuner

That RF tuner is quite new as it appeared devices less than one year ago. It is the latest tuner added to the RTL2832U reference designs until now (what I know).

Tuner is designed for digital terrestrial standards. Frequency range is from 42 to 1002 MHz, but it is said to to perform far more over that. Wide frequency range makes this tuner interesting, otherwise it is rather similar than typical DTV RF tuners nowadays. Everything but crystal is integrated, which mean less external components. No need for external LNA nor SAW filters (SAW filters are not needed since 1st generation silicon RF tuners, QT1010, MT2060, etc.).

R820T differs from the trend seen during last few years as it is not direct conversion aka zero IF tuner. That tuner is so called low-IF tuner, which means it uses intermediate frequency (IF) 5 MHz or less. Over the years, IFs used by DTV tuners has gone down from the ~50 MHz to few MHz or even zero (baseband). Compared to traditional superheterodyne architecture, direct conversion has many advantages like simpler architecture, lower power consumption and no harmful image frequency. Whilst direct conversion has many advantages it has some disadvantages too, most notable DC offset.

R820T power consumption

As this RF tuner has different architecture than all the other modern tuners used with the RTL2832U I decided to take some measurements to see how much more power it consumes than those which are based of direct conversion architecture. I used live 634 MHz DVB-T signal which has 8MHz bandwidth. That is very typical DVB-T transmission condition.

Here are the results, measured from the USB, nominal voltage 5V:
fc2580: 183mA
e4000: 176mA
fc0012: 166mA
tua9001: 186mA
r820t: 313mA

Architecture complexity has a price. It seems to drain around 135mA more current than Zero-IF tuners compared. I could assume it is pretty much same for all the the other low-IF tuners too that are designed during last 3 years or so.

PCB bottom side is empty

a lot of room for components
There is not much to say from that side of PCB. Few wires and two hole arrays, under the RTL2832U and R820T chips located other side. Those are for cooling. That device has a lot of empty room :)

USB interface

IDLE current drain without a driver: 110mA



Naked hardware #10: Hauppauge WinTV HVR 930C

About device

That USB device is so called hybrid television receiver as it supports both digital and analog TV. Supported digital television standards are terrestrial (DVB-T) and cable (DVB-C). It also supports FM-radio and has video inputs (S-Video and Composite video). Not to mention quite simple remote controller. All that makes it quite feature rich DTV USB stick!

Hauppauge has assigned USB ID 2040:1605 for that device.

Device is supported partially on Linux starting from the Kernel 3.3. Digital TV and remote controller is supported, whilst all analog stuff is not working.

Unfortunately there is currently new version available, with USB ID 2040:b130, that is not supported on Linux at the moment, as there is no Linux driver for used demodulator. New version has letters "HD" at the end of the name (Hauppauge WinTV HVR 930C HD). Stick itself looks same.

Lets teardown!

Hauppauge WinTV HVR 930C teardown

Hauppauge WinTV HVR 930C

Key components:

Empia EM2884
Micronas AVF 4910
Micronas DRX 3913K
Xceive XC5000

Sandwich PCB design

sandwich PCB
Device is constructed to two PCBs which are attached together like a sandwich. PCBs could not be separated without soldering. That kind of construction is not very common nowadays, but there is some others too, like PCTV nanoSticks. You could get a little bit shorter stick using sandwich design, especially in case of device having that many chips.

Gold colored connector, between the PCBs, near antenna connector is for analog video input. Composite video / S-video adapter cable is plugged to that connector.

There is two chips hidden between the PCBs. Those are USB interface and serial eeprom. Eeprom contains some configuration information as usually, like USB ID, USB strings, endpoint configuration and so. Hauppauge has assigned MAC address for that device too, which is very rare luxury nowadays! Honestly speaking, it is hard to see practical use scenario for MAC address. What I understand, it is aimed for IP transmission over DTV, which is not widely (not at all?) used nowadays. Anyow, it will not hurt anyone. MAC address is stored to that eeprom also.

Used USB interface chip is Empia EM2884. EM2880 series supports both digital and analog interfaces, whilst EM2870 has only digital interface. There is wide range of EM28xx chips, having different combination of features or just newer revisions chips with different chip model number.

EM2884 IR receiver is located opposite side of device. It could be hardly seen in that picture. Just typical IR-looking 3 pin black box.

RF tuner and digital demodulator

Micronas DRX 3913K and Xceive XC5000

RF tuner

Xceive XC5000 silicon RF tuner chip is located centre of the PCB. There is clearly visible copper square around the chip - likely left for possible RF shielding. Shielding is quite often used to reduce RF noise originating from the tuner. XC5000 is rather complex silicon tuner, designed for large scale of both analog and digital television standards. 32.000 MHz crystal, metal box left side of XC5000 in that picture, feeds clock for XC5000 tuner.

If you look carefully enough, you could see two wires between these two chips (XC5000 and DRX 3913K). There seems to be small 6 pin component (marked ARK X2) on that bus near tuner. That bus is either for control (I2C) or RF signal (intermediate frequency). I suspect it is RF signal bus and ARK X2 is switch that select whether to feed signal to analog demodulator or digital demodulator. That could be confirmed using oscilloscope if needed. Sometimes, especially when debugging problems, it could be nice to check signals travelling on that kind of buses, but unfortunately it is usually very challenging to find suitable pads to attach measure probes.

Digital demodulator

DTV demodulator used is Micronas DRX 3913K. It is one of the first multistandard demodulators having both DVB-T and DVB-C. Originally demodulator was made by Micronas but later these was sold to Trident Microsystems.

20.250 MHz crystal seen in picture is demodulator clock source.

DRX-K demodulator product family

DRX-K family contains following demodulators and them properties:
DRX 3916K: DVB-T, analog demod
DRX 3918K: DVB-T, analog demod, stereo decoder
DRX 3923K: DVB-C, DVB-T, analog demod, stereo decoder
DRX 3926K: DVB-C, DVB-T, analog demod

Analog demodulator

Micronas AVF 4910
That side of device is not so interesting as only visible chip is AVF 4910 analog demodulator. 20.250 MHz clock is get from the crystal visible on picture. It is just same clock frequency as used by digital demodulator on the other side. That chip is sometimes used in conjunction with DRX 3913K in order to provide both digital and analog television.

If you look this device, as a level how chips as are connected, analog demodulator is located between USB interface and RF tuner - just similarly as a digital side too.

digital RF path:
antenna =>  XC5000 => DRX 3913K => EM2884 => PC
analog RF path:
antenna =>  XC5000 => AVF 4910 => EM2884 => PC
analog video input path:
video input =>  AVF 4910 => EM2884 => PC

There is no Linux driver for that chip currently. Due to that, this device  video inputs and analog television is not working on Linux.

USB interface

IDLE current drain without a driver: 142 mA