This is a pretty shotgun question, but how hard would it be to interface an external GPS module to a smart-phone? Let's say case-modifying aside/module taped to outside with wires leading in, so just hardware and software discussion.
The GPS modules I'm thinking of are like this:
http://www.sparkfun.com/commerce/product_info.php?products_id=8621
This particular module has Tx and Rx Pins and outputs to standard NMEA format.
I personally have an HTC Hermes/Tytn1, but I'd guess this'd be applicable for most phones.
Related
Does anyone know what exact frequencies Sprint uses for Wimax ?
I made an external antenna port on my Evo, now it's time to make an external antenna itself
I'm seeing 2.5 GHz, I will look for continue to look for specifics
Wikipedia has a huge write up on WiMAX. I'm not sure the exact information your looking for, but under the technical information section, they pretty much give you everything.
Thank you
I know the theoretical range of Wimax, would be nice to know what frequencies people are seeing.
Does anyone know if in ##DATA#, Center Frequency is an actual freuqency phone uses to connect ? (Here are the values:* 2647000, 2657000, 2667000 I would assume it's 2.647Ghz/2.657Ghz/2.667Ghz) ?
However, if I go into ##33284# (FieldTrial / Wimax Engineering) it's* 2551500 for Center Frequency (after turning 4G Radio)
Anyone cares to share their ##DATA# and FieldTrial / Wimax Engineering ##33284# center frequencies ? I just want to see how much variation there is.
Its important to get as close to right frequency as possible when calculating segment length on antenna.
I am showing 2.525Ghz with the bandwidth of 10Mhz. What type of antenna are you going to use? I hope you have access to a Service Monitor to check the SWR of your antenna. How are you connecting the antenna to the phone?
Thank you for sharing kf2m
I am going to build omni-directional antenna based on this design (but from thicker cable)
_www.rason.org/Projects/collant/collant.htm
Unfortunately I do not have any equipment to check SWR.
As far as connecting an antenna to the phone, I've made a slight cut out on red cover where 4G antenna terminals are and attached small connector for center wire of coax cable to the terminals (I do not know about what to do with ground, but let's see if I get away without it). Black cover closes normally, without showing any modifications externally.
I will share results after the weekend, whether it's a success or fail
Sounds interesting. I haven't seen anything like this for the Evo. Please keep the thread updated, and if all works maybe a write-up?
~ I'm a fungi
arch111 said:
Thank you for sharing kf2m
I am going to build omni-directional antenna based on this design (but from thicker cable)
_www.rason.org/Projects/collant/collant.htm
Unfortunately I do not have any equipment to check SWR.
As far as connecting an antenna to the phone, I've made a slight cut out on red cover where 4G antenna terminals are and attached small connector for center wire of coax cable to the terminals (I do not know about what to do with ground, but let's see if I get away without it). Black cover closes normally, without showing any modifications externally.
I will share results after the weekend, whether it's a success or fail
Click to expand...
Click to collapse
That antenna is gonna be hot with common mode RF (hence the BALUM's at the base). Plus it is designed for 2 Meter operation, WIMax is like 10-11cm. I would not recommend using that. It also uses RG58 COAX which is way too thick, using thicker COAX like RG8 is going to be way too thick (massive line losses). The coax used for our purposes is about as thick as 14-16 gauge wire, RG58 is about 1/4", and RG8 about 1/2" thick. By design our phones use a 1/4 wave dipole antenna built into the chassis/frame. My measurements might be off but a full wavelength antenna is about 2.75" so a dipole antenna mounted vertically would be more effective, and without the grounding/ground plane issue you would have with an omni. At higher frequencies your SWR would be even more critical. Too high and your output circuit is going to overload from RF feeding back, and either pop the final output, or let out the magic smoke. A WiFi antenna is a close match, and using a LC matching circuit would be a better choice (or you can cut it down since WiFi is at 2.4Ghz, and WIMax operates at 2.5Ghz). Again you are going to need some sort of measuring device to properly match your antenna. Also using an antenna without a ground-ground plane, or reflector your SWR is going to be off the charts. To receive it is not much of an issue, but once you start pushing RF down the wire then it's a whole new ballgame.
Check here for some ideas.. http://www.dxzone.com/catalog/Antennas/WiFi/
Hope I gave you a bit more information to work with.
Good Luck
73 de KF2M
I've had excellent experience with pioneer and kenwood units that implement techniques to fall back on FM signal when the DAB coverage of a particular station is intermittent. They seem to use algorithms to time-align and perform volume matching on both signals, along with some buffering that allows them to perfectly switch to FM signal when the DAB service would otherwise cut out.
I am wondering if there's a combination of hard- and software that manages a similar solution that can be employed on MTCD units.
I think the DAB and FM have to be on the same chip for this and its only the non usb type DAB box for MTCB/D units that has an FM/DAB chip, it does support station following but I dont think its implemented.
Some one would have to mod the app to get it to work. theoretically you could write something to switch to the FM signal of the radio app if you have the usb DAB device.
Both Signals need o be fed to a Buffer.
Yes both dab fm or two dab signals are also possible.
Now audio signals need to be compared. This leeds to delay match which can the be used to align audio Volume and Frequency response. Regards Greg
Hi, I recently installed an MTCD px3 unit in my car but the audio quality is not that great. I'm looking at the option of a USB DAC but that appears to have its own set of issues and complexity.
I do note though that the RK3188 chip includes an SPDIF function and this does appear as an audio device in /proc/asound/cards so if the pins (balls) are exposed somewhere on the px3 module board then it should be just a matter of soldering to the right points to create an SPDIF interface.
If someone has a totally bricked unit would you consider doing some research? I.e. using some heat to the remove the RK3188 BGA chip and locating the ball that relates to SPDIF and seeing if it can be traced to a track?
The SPDIF transmitter is located at ball N20. You can find the datasheet by googling "RK3188 Datasheet" (sorry I can't post links yet). So who can "expose the balls"?
Alternatively if someone has a dead board/unit they would give away, I'd be happy to pay shipping for you to send it to me (in New Zealand) and I'll do the research and share my findings with the community.
Also looking for someone who understands what would be required on the software side of things to actually use the interface. Some kind of ALSA magic I guess?
Note - I do understand the limitation. I.e. this only applies to audio within Android, not the radio or bluetooth etc. My approach would be to install a physical switch so I could switch my car amp between the analog and digital outputs.
mcraenz said:
Hi, I recently installed an MTCD px3 unit in my car but the audio quality is not that great. I'm looking at the option of a USB DAC but that appears to have its own set of issues and complexity.
I do note though that the RK3188 chip includes an SPDIF function and this does appear as an audio device in /proc/asound/cards so if the pins (balls) are exposed somewhere on the px3 module board then it should be just a matter of soldering to the right points to create an SPDIF interface.
If someone has a totally bricked unit would you consider doing some research? I.e. using some heat to the remove the RK3188 BGA chip and locating the ball that relates to SPDIF and seeing if it can be traced to a track?
The SPDIF transmitter is located at ball N20. You can find the datasheet by googling "RK3188 Datasheet" (sorry I can't post links yet). So who can "expose the balls"?
Alternatively if someone has a dead board/unit they would give away, I'd be happy to pay shipping for you to send it to me (in New Zealand) and I'll do the research and share my findings with the community.
Also looking for someone who understands what would be required on the software side of things to actually use the interface. Some kind of ALSA magic I guess?
Note - I do understand the limitation. I.e. this only applies to audio within Android, not the radio or bluetooth etc. My approach would be to install a physical switch so I could switch my car amp between the analog and digital outputs.
Click to expand...
Click to collapse
Hi.. my Android Radio just recently crashed. If you like.. i can give it to you.
Its a Hot Audio Android Radio PX3 RK3188.
Thanks very much. I've sent a PM.
Cheers,
Rhys
do you located SPDIF transmitter? Is possibile to connect directly an external DSP such Audison P8.9?
Bump
Since I've purchased the Joying JY-UQD11N6G I have had nothing but problems with it. Such as:
The device will not power off or sleep when the ignition is switched off no matter the configuration.
The connected amp constantly remains on.
4G does not work with one of the suggested provider's SIM (T-Mobile). The SIM is recognized, works in other phones, but zero bars. Support has zero solution, and the solution in the blog does nothing.
A one pixel wide red line from top to bottom exists in the display. Support will not replace it.
These are just a few of the issues. So i've decided to scrap the board. I'm going to keep the display and the case and put either a Raspberry Pi 4 or a Radxa Rock 3a w/ 8GB of RAM in the case. I'll put a Hi-fi Berry hat or something similar on top for digital audio output and 5.1 signal processing to run to the amp. I could really use some help with the pinout of the UIS7862 40 pin display connector from the community. I can't find this or a schematic for the device anywhere. I'm not certain if this is just using the same protocols as the GPIO standard or if it's something custom.
Looking inside the display case one finds a board with a large 40 pin connector on the back. Its mipi dsi/csi to edp converter is the Lontium LT8911EXB chip, but the board has no part number on it, so again, I can find no schematics/manual. Both the LCD display connect to this via a 40-pin ribbon and 2-pin wire harness, and the capacitive touchscreen via a 6-pin ribbon. I've attached pics of the board and the PDF that has some info about the chip.
So I'm not sure if the display connector on the UIS7862 is an unconventional adaptation of a DSI 40-pin output or a GPIO interface, but whatever it is, it carries the display data, touch data, and power for both. If anyone has a schematic showing the pinout, the actual FYT manual from this year or the last few years, or any information about this display that would be appreciated!
Bump
It looks like the sockets on my tv box where the antenna connects to the main board.
Looks like a MHF connector, fairly common on older devices for some reasion. Not really sure why, maybe manufacturers envisioned being able to use external antennas to boost reception? Or maybe it's for some sort of vehicle phone mount that would have a mating connector for an external antenna.