$10 China GSM Phone

We have seen how new Iphone shakes the market. How about low tech phones  and how much a handset cab be cheap? Last year, I saw Bunnie’s blog post about a cheap $12 Gongkai handset from Mingtong Digital Mall in Shenzhen.  Gongkai means “Open” in Chinese and it’s the term alternative of “Open Source”. Mingtong Digital Mall is one of the famous digital gadget’s malls from Shenzhen especially cheap and copy items. I wondered how these cheap handset could be sold in this low price when I saw his blog post.

www.bunniestudios.com/blog/?page_id=3107

I lived in Myanmar, yes a green land opened it’s door recently. The government released telecom sector and has given the two new operators, Telenor and Ooredoo. Just a clarification, some may don’t know how Myanmar telecom sector is squeezed before 2000. I bet you will wonder how much it will cost for a mobile SIM card before 2000. It was cost about $5000 (Please up your jaw, I am not kidding :D). In last decade, owning a mobile phone was a trade mark of being a “boss” in Myanmar. Most people used a public pay land lines phone booth in every sight of cites. Seem these will soon be a history. But for now, news operators are moving and it costs  about only $1.5.

Have you ever seen people queuing for a cheap SIM card?

 

Yesterday, one of my colleagues showed me a GSM handset with a surprised price tag, 10000 MMK.  It is about $10 (1$ = 986 MMK). I quickly checked specs and my curiosity leaded me to bought one. It is a normal low price GSM handset with basic functions. I saw many cheap China handset but non are not lower than $20. This is the cheapest handset I have ever seen. Note that Bunnie’s Gongkai Phone is $12 at China, main land but I bought my $10 phone from local retail shop from Mandalay, Myanmar. More surprising fact is that my friend told me wholesale price is >$9. If this is right, how much it will be the ground cost of these handset in it’ts origin, China!! Unbelievable. Here is my cheapo handset. It is just ordinary phone but specs are even a little higher than Bunnie’s phone come with a box, handset, a battery, charger and a hands free earpiece.

DSCN7341 DSCN7344

 

The spec and functions listed on the box,

  • Touch
  • FM Radio
  • Music Player
  • Video player, recorder
  • MicroSD
  • Camera
  • Bluetooth
  • Multi languages
  • 1.8″ Display
  • Dual SIM (Dual standby) , Stereo Speaker (Really, only one Speaker), Games

DSCN7342 DSCN7343

 

The brand is Soloking and model is T176. I quickly searched google and searched more info. superfone.en.alibaba.com/product/1807438912-215027443/T176_1_8inch_soloking_china_mobile_phone_cheap_price_celulares.html

  • Platform                       : coolsand 8851
  • Operation System      : Mstar
  • Build in memory        : 32+16 Mbt
  • Frequency                    :  GSM 900/1800   optional   850/9001800/1900
  • Multi Media                 : MP3/MP4/3GP/FM Radio / Bluetooth Camera 0.3 Mega Pixels
  • Multi Function Torch : Alarm ,Calendar ,Calculator ,Audio recorder ,Video recorder
  • Flash Card Support     : T-Flash Card Max support to 8GB
  • Languages Multi language : Arabic,French,Turkish, Thai,Vietnam,Russian, English, Hindi, Indonesian, Spanish etc

I installed battery, SIM and power up the phone.

DSCN7347

 

Tested basic functions call, menu, camera, FM etc. DSCN7352 DSCN7356 DSCN7359

- FM

DSCN7360

- It supports Java.

DSCN7361

It even include Myanmar language support. Changed and tested it but some menu were not properly show :) .

DSCN7357   DSCN7358

Finally, I teared down to check how these cheapo was made.

DSCN7363 DSCN7345

Just removed 4 x small screws, everything disassembled.

DSCN7366   DSCN7374     DSCN7369 DSCN7372

 

Other are usual parts such as speaker, mic,  SIM holder, SD slot, small camera, FM antenna and 2 x LEDs for torch. The phone is controlled by all in one chip.  The back side Speaker housing is attached with multi-band antenna.

  • LCD, this must be a friendly 1.8″ SPI TFT, LCD  (ST7735 controller ) from hobby shop around the world. I even ordered these LCD from elecfreaks  last a few months ago.
  • There is a EMI shield which covered the chip but google infos and some partially label can able to guess  me the main chip. It is RDA8851 from RDA Microelectronics, one of chip manufacturer from China. In short, it’s all in one chip which doo everything for phone such as baseband, interface, Bluetooth, FM, camera, Flash (32Mb build in), UART, SPI, I2C etc. Here is the links to chip datasheet.
  • www.rdamicro.com/products/Detail_238.aspx
  • Firmware is Mstar from MStar Semiconductor, Taiwan . From  Wiki , MStar is often referred as “Little-M” in Chinese community, as a contrary part of the bigger company “Big-M”, MediaTek.

- The only weakness of this phone (in comparable this price) is it’s charger. I also opened and checked the charger design. It voids all of safety rules. Manufacturer should include a more safe charger with a buck. The stock charger is one of the simplest and reduced version without any protection of it’s line. The design includes 13001 NPN Epitaxial Silicon Transistor,  1 IN4001 diode rectifier, small SMPS transformer, 5V zener, 3 capacitors and some resistors, that’s all. The output voltage is about 6V.

DSCN7379

Final thought:

- First, I don’t expect much from this phone but the price is really amazed for me. It is a bare phone without no contract and unlocked. It exported from china to Myanmar. What will be local retail price and how much it can be lower?

- The cost of the phone is the parts and production costs plus a little export costs. There will be absolutely NO licensing, copy cats fee :) and seem no certification.

- Everybody talks about SAR. But I think the RDA chip can take care of this in a basic level. The package label state that SAR Head : 0.342 W/Kg(1g) and body : 0.429 W/Kg (1g).

- I know that designing a mobile phone is not that hard. I designed my own DIY mobile phone recently with a basic functions like this phone with the same LCD. Even LCD it self costs about $6.4  in some ebay retail shops. What will be the lowest bargain price of this LCD? (I believe the LCD must be the most value part in this phone. Any idea?)

- For the chip, I don’t know how much cost for this RDA chip in volume and in retail. Bunnie said that MT6250 chip from his Gongkai Phone in retail price is $2.1.

- If someone knows about these, let me know and also share your thought.

Last :

Again, it is not rocket science to build a mobile phone. This is my DIY GSM mobile phone prototype which I recently developed for fun and hobby. Some basic functions such as call, sms, GPS are done and still working for a complete prototype. But, you may not defeat China at least in quantity and cost :D. Thanks for visiting.

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By oakkar7

okelectronic.wordpress.com

ISEE3 Rebooted

This post is an honorable post to a group of  Citizen Scientists and Volunteers for their effort to reboot an cold world era (launched 1978) satellite which floated around the universe.

Source: http://www.planetary.org/ NASA International Sun-Earth Explorer (ISEE-3) The International Sun-Earth Explorer (ISEE-3) launched in 1978 on a mission to study Earth’s magnetosphere. In 1983, it became ICE, the International Cometary Explorer, and was sent on a new mission to study comets Giacobini-Zinner and Halley.

Mission control team used GNURadio (opensource SDR radio software) to wake up and control the runaway bird.

http://www.fsf.org/blogs/community/free-software-in-space-gnu-radio-and-the-isee-3-spacecraft

And they used the huge monster disk Arecibo because this is the only dish on the planet to reach that distance so far.

 

 

A nice , simple and clean mission control room. This is different from the war room we have ever seen.

 

isee3.team

ISEE-3 Reboot Project Mission Control Team

http://spacecollege.org/isee3/

https://twitter.com/ISEE3Reboot

It was 10 July 2014 early morning, I was waiting for World Cup, surfed the net and follow their twitter stream about TCM burn (the mission control team started and burned a series of thrusters). And they also feed the live telemetry data. I followed their tweet and live data stream.

DSCN7251

2014-07-10_013106

2014-07-10_011305

 

This shows how a crowd funding and citizen scientists can go far. And this is the first collaboration project with public for space science.

Congratulation to all.

okelectronic.wordpress.com

 

RTL-SDR & FUNcube

While World Cup was continuing its exciting show, I made some my RTL-SDR and satellite research progress. My next target was FUNCube Sat (aka) FUNcube-1 (AO73) is a complete educational single CubeSat project with the goal of enthusing and educating young people about radio, space, physics etc.

http://funcube.org.uk/

http://amsat-uk.org/funcube/funcube-cubesat/

There is one thing that Funcube is magnificent than others, it’s data warehouse. The earth station can receive its telemetry data and can upload this data to data warehouse by online. There is also Dashboard Application for telemetry data decoding and uploading to data warehouse.

Here is the link for those who interested.

- Funcube Handbook 

- Data Warehouse

- Dsahboard Application

N4JTC wrote about RTL-SDR and Funcube  , I followed this.

http://n4jtc.wordpress.com/2013/11/23/rtl-sdr-sdr-radio-funcube-sat-fun/

This time SDR Radio V2 software was used because this software has some distinct features such as sat tracking and I liked to test it. I believe that any rtl-sdr app can do this.

- http://v2.sdr-radio.com/Download.aspx

 

OK, before world cup final match, I do this. I tuned 145.9xx MHz and saw waterfall data stream and audible beep. It is SSB data.

funcube_manualtuning

Then, piped audio data stream to Dashboard application. The telemetry data show up.

2014-07-11_113953

 

I already registered to Data-warehouse sites and Dashboard App automatically uploaded to warehouse site. Then, my uploaded data appeared in site. Seem I am the only one and first data provider earth station from Myanmar.

 

funcube_datawarehouse2

# Final thought

- Noticed some noises along with the whole spectrum and some recommend for shielding. I have to test it. Anyway, shielding an RF device is a best practice. Hree is the link for this. I will try this.

http://sdrformariners.blogspot.com/2013/09/reducing-electrical-noise.html

Anyway, it is happy research and hobby time.

okelectronic.wordpress.com

 

 

 

 

RTL-SDR Second Attempt

After leaving my RTL-SDR for one year, last month, I had a chance to test it again. Yes, last month , World Cup 2014 began on June and ended on July. How World Cup was related to RTL-SDR testing? Due to the east and west time zone differences, local time for match schedule in my country (Myanmar) is beyond midnight. It was a chance to make, test something while waiting for the matches.

I remember an article about tracking hobby, educational satellites with rtl-sdr. Goggled and found out these articles, good to go.

Tracking NOAA Weather Satellite with RTL-SDR,

http://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-noaa-weather-satellite-images/

Then, checked when NOAA sats will passed my location from these satellite tracking websites.

http://www.n2yo.com/

http://www.satview.org/

Checked that active sats regularly pass my location before midnight. Great, that is how I my rtl-sdr was related to world cup :D.

I read article and follow instructions thoroughly. Installed required software,

  • SDR# for receiving Sats
  • VB-cable for audio piping from rtl-sdr to sound card
  • Orbiton  for tracking satellites
  •  WXtoImg for decoding the APT signal

Most of rtl dongles have more or less tuning freq error. After finished installation of all software, I calibrated freq ppm error with these instruction. It is sample, monitored local GSM freq band and  adjusted error.

http://rtl-sdr.sceners.org/?p=193

1# Antenna

What I need was an external antenna for 137~145 MHz reception. I built Ground Plane antenna in an evening because this is easy to build.

Each antenna element = 51 cm, used old N type RG213 male connectors for assembly.

DSCN7239

 

 

 

 

 

 

 

 

Finished and installed antenna.

DSCN7253

 

After tuning and trials, I track and tuned NOAA-15 satellite signal successfully.

2014-07-08_034255

But the decoded image was noisy and not good.

2014-07-11_174754

2# Second Antenna (QHF)

After several attempts, I realized that a good antenna was required for better reception. So, I tried to build second DIY antenna. After a few research, I chose Quadrifilar Helix (QFH) antenna type.

Design calculation can be done here.

http://jcoppens.com/ant/qfh/calc.en.php

And here is ready made design by G0HPO.

 

First , collected required copper wire (12 gauge, enamel), female RG213 connectors, coax-cable , wood rod etc. Then, tried to bend, loop copper wire for helical shape.

DSCN7241

 

Soldered feed point with the help of small PCB.

DSCN7242

 

Loop the balun and connector.

DSCN7243

 

Final assembly, also attached recycled  rain drop covers for feed and connector :D

DSCN7247

 

 

 

 

Hoisted the antenna, ready to go.

DSCN7252

 

As expected, second attempt results ware not so bad. The receiver show more stronger signal than first antenna.

2014-07-09_023511

 

There are still noises in receptions when sat is at lower azimuth.

Some results,

2014-07-11_175443

2014-07-11_175323

 

# Results

- QHF antenna is better reception than Ground plane

- BUT, QHF is a lot noisy than Ground plane

- Do I need parabolic or YaGi with tracking ?? for next

# Final thought

Sure, I need LNA for next and future test. Need to find out the list for DIYable LNA.

http://www.rtl-sdr.com/tag/low-noise-amplifier/

http://blog.kf7lze.net/2012/09/14/round-up-of-rtlsdr-upconverter-choices/

 

Fun midnight modern hamming while waiting for World Cup.

 

http://okelectronic.wordpress.com

 

 

RTL-SDR First Experience

Last year, I heard about cheap SDR using DVB-T USB stick. Like everybody else, I quickly found and bought one of these RTL chip base dongle from local supplier.  My dongle is this one. It is ezcap DVB-T stick, model EXTV668 ver 8.0. This stick work well with most RTL-SDR software. I tested it with SDR#, HDSDR, SDR-RADIO.COM V2.

After testing some program and tuning local FM stations, I leaved this dongle for year.

List of compatible software is here,

http://www.rtl-sdr.com/big-list-rtl-sdr-supported-software/

Most helpful resource and credited sites are;

http://www.rtl-sdr.com/

http://rtlsdr.org/

Quick start guide,

http://www.rtl-sdr.com/rtl-sdr-quick-start-guide/

 

DSCN6460

DSCN6463

 

Listening Mandalay FM 88.9 MHz…loud and clear, you’re 59 ….

88.9FM

GTP-USB-Lite Programmer re-flsahed as USBPICProg

I bought this programmer from local supplier a few years ago. This is a GTP-USB-lite programmer clone and beautifully build as sandwich  style.

USB-PIC_Prog (2)

 

USB-PIC_Prog (3)

Some drawbacks of this programmer are:

  • I noticed that this programmer don’t work with some PC/Laptop USB port for unknown reason.
  • Don’t support Windows 7
  • Not opensource,

 

Anyway, GTP-USB programmers are the best and DIY friendly at their age. Mostly, I used PicKit2, PICKit3 as main programmer. So, I leave this programmer in a corner of my desk for a while. Last week, I noticed a post in DP forum about hacking aka flashing this programmer.

http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=6305

The original blog post here.

http://www.valpoder.com/?p=268

At the last weekend, I try to flash my GTP-USB-Lite programmer with new firmware and to use new software. The procedure is very simple.

- GTP-USB-Lite and USBPICProg are very identical hardwares, USB interface, PIC18F2550, the same charge pump, same programming header’s pin.

- The difference are;

  • GTB-USB lite used 8MHz crystal and USBPICProg uses 12 MHz crystal
  • LEDs are connected at PIC pins 11,12 and 13 in USBPICProg and pins 27,28 at GTP-USB-Lite.

GTP-USB-Lite hardware circuit

USBPICProg hardware , firmware, PC software (The best thing is  all are opensource :D)

- First, to take off and flash programmer’s PIC18F2550 with boot loader and to change 12MHz crystal in circuit

USB-PIC_Prog (4)

 

 

- Download and installed PC software and install it.

- Download last firmware and  attached programmer. The PC will detect bootloader and install bootloader USB interface driver. Launch the PC programmer software and  bootloader is activated and update firmware.

- USBPICProg-0.6.0-software –> Updated Firmware

- Then, remove programmer from USB port. Connect PGC pin (RB6 , Pin No 27 of PIC18F2550) to ground to de-activated the bootloader and activated USBPICProg programmer mode. The PC USB port will detect and installed new device (USBPICProg) driver.

Before final launch, I simply cut the trace between LEDs and  RB7,RB6 (pin 27,28) and connected LED’s resistors to Pin 11,12. LED shows signal now.

USB-PIC_Prog (1)

 

For now, I can use reborn USBPICProg as a backup programmer. I renamed it USBPICProg because it is no more GTP-USB Lite.

USB-PIC_Prog

Cheers!

 

http://okelectronic.wordpress.com/

 

Microchip Advanced Parts Selector and other handy tools (Online/Offline/Mobile vers)

I used PIC as my primary development platform for years. Selecting a right MCU and checking features while developing is a time consuming task sometimes. Last week, I noticed handy tools in Microchip website.

The first tool is Microchip Advanced Parts Selector (MAPS) tool. There is online and also offline version. I tested both quickly. Online and offline version are same interface. Great, can search, filter and compare various PIC easily.

The link : http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1924&dDocName=en544123

MAPS_1

There is also a mobile version for both Android and IOS platforms named Mobile Product Selector.  It is also handy to use with your tablet at workbench while testing something.

Android App Link: https://play.google.com/store/apps/details?id=com.microchip.andriod.mmps&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5taWNyb2NoaXAuYW5kcmlvZC5tbXBzIl0

Mobile_Product_Selector

Wait, there are also some good tools for discrete components, Analog and Interface Products Presentation – (Offline Only). This is a power point file with good linking. You can click and find right info for interface , analog peripherals and  parts like transceiver, op-amps etc..

Microchip_Parts_infos

Last one is “Product Tables”, all PIC with required info and volume pricing can be downloaded as PDF or CVS format.