I solved this problem today. I have a Le Pan TC-970. The problem is that
android 2.2 has no regular (and easy) way of updating the security
certificates used for secure network communication.
When I try to visit netflix.com I get this error message about the
certificate cannot be trusted. I knew that that means the key corresponding
to the security certifcate netflix is using is not present in the tablet's
key database.
I suspected this may also have to do with the netflix app error (13001).
I googled around for sometime to find how to update the tablet's security
key database.
I came across this howto:
http://wiki.cacert.org/FAQ/ImportRootCert?action=show&redirect=ImportRootCert#Android_Phones
It was clear android 2.2 has no way of updating the key store. To use the
method in the how to you need to root the device. And that is what I did.
To root the device I followed:
http://forum.xda-developers.com/showthread.php?t=1483954
Netflix is using a certificate issued by GeoTrust DV SSL CA .
I downloaded all the regular (not the application specific ones) root
certificate files from :
http://www.geotrust.com/resources/root-certificates/
You also need to install android sdk on your computer for the adb shell to
communicate with the tablet. I use ubuntu on my computer. So I followed
:
http://forum.xda-developers.com/showthread.php?t=921169
Android 2.2 stores the certificate keys in a file
/system/etc/security/cacerts.bks
which is read-only normally. To modify it you need root permission and
hence the need for rooting.
You can pull the file from your computer by an
adb pull as explained in the howto. I also needed to convert the downloaded
security files
to the der format.
Now you have to insert the new key files to the cacerts.bks using the
keytool command and the updated cacerts.bks need to be sent to the tablet
using a adb push command.
Before the adb push you need to remount the
/system partition in read-write mode and change the permissions on the
security folder from the adb shell.
Once the new cacerts.bks is installed (copied) in the tablet it need to be
rebooted.
After that the app worked fine and no more security error messages while
netflix.com from the browser.
While remounting the system partition in read-write mode you may need
device name in TC-970 viz /dev/block/mtdblock3 . The adb shell command
is:
mount -o rw,remount /dev/block/mtdblock3 /system
Hope it helps somebody.
It seems to me that, for netflix to fix it google needs to send an update
to android 2.2 . It is also possible that netflix hasn't figured out the
what is causing the problem.
Arun
Monday, September 2, 2013
Monday, November 28, 2011
A used car buying guide
You don't need a mechanic to make a good judgement about the condition of the car. This is a set of things I put together to help me with my next used car purchase.
1. There should be no fluid marks on the ground where the car was parked. Any marks should indicate that some fluid is leaking from the car. Some fluid leaks, especially leaks from the engine and transmission, could be expensive to fix.
2. Automatic transmission fluid should be clear red, no burned smell and the level should be correct. When the brake or clutch pads inside the transmission wear they make the fluid murky and leave a burned smell. (The level of transmission fluid is checked when the engine is running, as the fluid should be pumped to the torque convertor for its operation. When the engine stops the fluid drains back to the reservoir increasing the level above spec.)
3. The engine oil level should be close to the maxline, which is where the garages usually fill upto. So any decrease in level should be due to oil leaking out or burning inside the engine both of which are bad. Some engines burn oil due to stuck oil control rings on the pistons or leaky valve stem seals. Oil burning typically worsens over time. Oil control rings on the pistons cannot be fixed without a complete tear down of the engine, which is sometimes as expensive as replacing the engine. Fixing the valve stem seals is not cheap either.
Engines in good condition consume only a small amount of oil between recommended oil changes and the oil normally looks brown to dark brown. Big drops in the oil level in the absence of leaks and oil burning should indicate the previous owner hasn't changed the oil for a long time: often a red-flag pointing to poor maintenance habits.
4. Check the color of the tail pipe (exhaust) smoke when the car starts from cold state. There should be very little visible smoke if any from the tail pipe. Lots of smoke, if present, could be due to oil leaking into the ignition chamber due to leaky valve stem seals. Presence of visible smoke once the engine is warmed up could be due to stuck piston oil control rings.
5. Inspect the engine outer surfaces for oil stains and deposits. Significant oily dirt accumulation is not good sign, as it could be due to leaky gaskets.
6. Inspect the body of the car for rust, especially inside surfaces around the periphery of the doors.
7. When the engine is idling there should not be any excessive vibration inside the car. Excessive vibration is often a sign of one or more worn out engine mounts.
8. Engage the power steering end-to-end from left to right and back, when the car is stationary and listen for any abnormal sounds or grinding noises. There should not be any unusual sounds.
9. If the car has power windows make sure all the windows are working.
10. Check if the tires are excessively worn, in which case you may want to ask for a discount to defray the costs of an imminent tire replacement.
When you test drive
11. Make sure that the gear shifts are smooth (should not be jerky) and are happening at the expected times in the case of an automatic transmission.
12. Observe the feel of the brakes.
13. Observe the smoothness of the ride, the acceleration, power etc.
14. Ask for past service and maintenance records. Such record keeping is often a good sign of proper care by the previous owner. Also it will be handy for you to determine when the next service items are due.
1. There should be no fluid marks on the ground where the car was parked. Any marks should indicate that some fluid is leaking from the car. Some fluid leaks, especially leaks from the engine and transmission, could be expensive to fix.
2. Automatic transmission fluid should be clear red, no burned smell and the level should be correct. When the brake or clutch pads inside the transmission wear they make the fluid murky and leave a burned smell. (The level of transmission fluid is checked when the engine is running, as the fluid should be pumped to the torque convertor for its operation. When the engine stops the fluid drains back to the reservoir increasing the level above spec.)
3. The engine oil level should be close to the maxline, which is where the garages usually fill upto. So any decrease in level should be due to oil leaking out or burning inside the engine both of which are bad. Some engines burn oil due to stuck oil control rings on the pistons or leaky valve stem seals. Oil burning typically worsens over time. Oil control rings on the pistons cannot be fixed without a complete tear down of the engine, which is sometimes as expensive as replacing the engine. Fixing the valve stem seals is not cheap either.
Engines in good condition consume only a small amount of oil between recommended oil changes and the oil normally looks brown to dark brown. Big drops in the oil level in the absence of leaks and oil burning should indicate the previous owner hasn't changed the oil for a long time: often a red-flag pointing to poor maintenance habits.
4. Check the color of the tail pipe (exhaust) smoke when the car starts from cold state. There should be very little visible smoke if any from the tail pipe. Lots of smoke, if present, could be due to oil leaking into the ignition chamber due to leaky valve stem seals. Presence of visible smoke once the engine is warmed up could be due to stuck piston oil control rings.
5. Inspect the engine outer surfaces for oil stains and deposits. Significant oily dirt accumulation is not good sign, as it could be due to leaky gaskets.
6. Inspect the body of the car for rust, especially inside surfaces around the periphery of the doors.
7. When the engine is idling there should not be any excessive vibration inside the car. Excessive vibration is often a sign of one or more worn out engine mounts.
8. Engage the power steering end-to-end from left to right and back, when the car is stationary and listen for any abnormal sounds or grinding noises. There should not be any unusual sounds.
9. If the car has power windows make sure all the windows are working.
10. Check if the tires are excessively worn, in which case you may want to ask for a discount to defray the costs of an imminent tire replacement.
When you test drive
11. Make sure that the gear shifts are smooth (should not be jerky) and are happening at the expected times in the case of an automatic transmission.
12. Observe the feel of the brakes.
13. Observe the smoothness of the ride, the acceleration, power etc.
14. Ask for past service and maintenance records. Such record keeping is often a good sign of proper care by the previous owner. Also it will be handy for you to determine when the next service items are due.
Saturday, October 22, 2011
Corolla 1996 power steering pressure hose replacement
Yesterday I replaced the power steering pressure hose that has been leaking for a long time. Lately the leak has worsened to a spray. I bought the replacement part from Autozone for $26.99, Duralast Power Steering Pressure Line Hose (With O-Ring fitting), Part Number: 71782. This is a much lower price than the toyota oem price which is close to $200.
Removing the banjo-bolt near the pump was easy, with a 22mm socket connected to an extension did the trick. Collected the fluid drained using a pan under the vehicle near the passenger side wheel. The bottom end of the hose connected to the power steering gear box turned out to be a bit hard to remove, because there is no room to apply a wrench there. A socket cannot be used because the pipe is in the way. Finally, had to use a crowfoot wrench (17mm) connected to a 24 inch extension. The extension was inserted through the small opening through which the brake line comes out near the driver side wheel. Disconnected the bottom end and collected the fluid into the pan. After disconnecting the top and bottom ends of the hose, I also had to remove one 10mm bolt and loosen another both of which secure the pressure line and the return line to the chassis. This was particularly cumbersome and had to do by extending both arms down behind the engine from above. Once the old hose was removed, it was easy to put in the new one. There is an o-ring at the bottom end and two copper washers at the top end, one each on either side of the banjo bolt. The new hose needed a 5/8" crowfoot wrench at the bottom end.
After installing the hose, valvoline dex/merc automatic transmission fluid was filled in the power steering reservoir and started the engine and rotated the steering wheel end-to-end several time. Switched off the engine, topped-off the fluid and repeated. After that the fluid level was steady, so the air must have been out.
Now it was time to congratulate myself. The workshop quoted $135 for labor alone. It took me 3 hours to do it. Not bad.
Removing the banjo-bolt near the pump was easy, with a 22mm socket connected to an extension did the trick. Collected the fluid drained using a pan under the vehicle near the passenger side wheel. The bottom end of the hose connected to the power steering gear box turned out to be a bit hard to remove, because there is no room to apply a wrench there. A socket cannot be used because the pipe is in the way. Finally, had to use a crowfoot wrench (17mm) connected to a 24 inch extension. The extension was inserted through the small opening through which the brake line comes out near the driver side wheel. Disconnected the bottom end and collected the fluid into the pan. After disconnecting the top and bottom ends of the hose, I also had to remove one 10mm bolt and loosen another both of which secure the pressure line and the return line to the chassis. This was particularly cumbersome and had to do by extending both arms down behind the engine from above. Once the old hose was removed, it was easy to put in the new one. There is an o-ring at the bottom end and two copper washers at the top end, one each on either side of the banjo bolt. The new hose needed a 5/8" crowfoot wrench at the bottom end.
After installing the hose, valvoline dex/merc automatic transmission fluid was filled in the power steering reservoir and started the engine and rotated the steering wheel end-to-end several time. Switched off the engine, topped-off the fluid and repeated. After that the fluid level was steady, so the air must have been out.
Now it was time to congratulate myself. The workshop quoted $135 for labor alone. It took me 3 hours to do it. Not bad.
Saturday, October 23, 2010
Home energy use
I did some calculations on the energy use in my house which I share with two other people. Our energy expenditure is a bit too high to my taste. Partly it has to do with the old house whose insulation may be lacking. The outdoor AC unit is probably operating inefficiently because of old age. The service person said its coils and fins are clogged with dust and dirt. The landlord does not seem too enthusiastic about cleaning or replacing it as it technically works. But in peak summer it kind of works all the time and still struggles to bring the inside temperature around 75F. I did my best to seal any leakage through the door and window edges.
Our utilities charges from 2009 Sep to 2010 Sep are respectively as follows:
$ 153, 153, 339, 333, 288, 381, 171, 150, 330, 375, 366, 450 .
That would make average cost $290. Per head $97 .
You see we are not the greenest people around. I really wish we didn't use this much energy.
I couldn't do much about the AC . The housemate upstairs is very sensitive about heat.
I am trying to employ a space heater for my room in the winter to see if I can save on the gas for heating. I am more sensitive to cold in the winter than heat in the summer.
I find that the highest gas bill in the winter was $239 and the lowest gas bill in the summer was $35. So the difference I assume is roughly from the centralised heating in the winter and that is roughly $200.
The highest electricity bill in the summer cost $339 and the lowest electricity bill in the winter cost $89 . I assume the difference roughly came from the AC in the summer and that is $250.
The electricity costs more than the gas in our house, though the costs are comparable. By using a space heater I am trying to trade electricity for gas, though hopefully more efficiently.
The electricity costs roughly 18 cents/KWh in a month in which the electricity bill is $178 which is kind of our average bill.
That mean if I can get by with the space heater which is rated 1.5KW on for 5hrs / day it would cost $40 . If it leads to only 50% usage of the centralised gas heating its cost will be down by 50% that is $100. The overall saving in that case will be $60. Not bad. Also, it may be warmer in my room this winter.
By the way the heater I purchased is Honeywell Electronic Ceramic Heater from target. There was only a store model left which I purchased for a 15% discount at a price of $23 .
http://www.amazon.com/Honeywell-Electronic-Ceramic-Heater/dp/B000TGX58E
I am happy with this heater. It is not the quietest thing. I wouldn't be making any audio recording with this thing on. It has a little more sound than the a fan. It doesn't bother me much.
Our utilities charges from 2009 Sep to 2010 Sep are respectively as follows:
$ 153, 153, 339, 333, 288, 381, 171, 150, 330, 375, 366, 450 .
That would make average cost $290. Per head $97 .
You see we are not the greenest people around. I really wish we didn't use this much energy.
I couldn't do much about the AC . The housemate upstairs is very sensitive about heat.
I am trying to employ a space heater for my room in the winter to see if I can save on the gas for heating. I am more sensitive to cold in the winter than heat in the summer.
I find that the highest gas bill in the winter was $239 and the lowest gas bill in the summer was $35. So the difference I assume is roughly from the centralised heating in the winter and that is roughly $200.
The highest electricity bill in the summer cost $339 and the lowest electricity bill in the winter cost $89 . I assume the difference roughly came from the AC in the summer and that is $250.
The electricity costs more than the gas in our house, though the costs are comparable. By using a space heater I am trying to trade electricity for gas, though hopefully more efficiently.
The electricity costs roughly 18 cents/KWh in a month in which the electricity bill is $178 which is kind of our average bill.
That mean if I can get by with the space heater which is rated 1.5KW on for 5hrs / day it would cost $40 . If it leads to only 50% usage of the centralised gas heating its cost will be down by 50% that is $100. The overall saving in that case will be $60. Not bad. Also, it may be warmer in my room this winter.
By the way the heater I purchased is Honeywell Electronic Ceramic Heater from target. There was only a store model left which I purchased for a 15% discount at a price of $23 .
http://www.amazon.com/Honeywell-Electronic-Ceramic-Heater/dp/B000TGX58E
I am happy with this heater. It is not the quietest thing. I wouldn't be making any audio recording with this thing on. It has a little more sound than the a fan. It doesn't bother me much.
Saturday, August 7, 2010
Clear iSpot experiment
I ordered the Clear iSpot taking advantage of their promo offer. I wanted to check out the wimax/4G. Since the iSpot offer is affordable and contract-free I could not resist.
I received it the next day after I ordered. That was shipped to DC by UPS next day air from Las Vegas. After opening the box it took only a few minutes to put the battery in and see that I only have a week signal (signal indicator red) in my room.
Getting online was a bit more involved as I do not own any apple devices and iSpot is restricted by Clear to work only with apple devices. It was reported that they use mac address to identify and filter out non-apple devices. It is supposed to be easy to spoof a mac address with linux.
I tried the command to set the MAC address where x's are replaced by some hex digits (0-9 or A-F) and eth1 is my wifi interface. (I use ubuntu linux which has the command macchanger available from apt-get)
sudo ifconfig eth1 down
sudo macchanger -m 00:1D:4F:xx:xx:xx eth1
sudo ifconfig eth1 up
Unfortunately my computer and laptop have broadcom wifi and apparently their driver has some problem. After I changed the MAC address they will no longer associate with any wifi including mine. Upon searching the web I saw other people complaining the same.
Luckily I had a usb wifi adapter (Alfa awus036h) which uses realtek 8187L wifi.
Even that was having some difficulty associating after the MAC address was changed.
Finally I added the command to /etc/rc.local and restarted the machine and then it worked.
I was online soon after I entered the wpa password given on the label underneath the iSpot.
The configuration page located at 192.168.1.1 showed that my wimax signal strength was -80 to -82 dBm . A speed test using speedtest.net showed that I get around 2Mb/s download and 0.5 Mb/s upload . There was significant delay for the websites to start loading which I narrowed down to the delay in dns resolution. It was later fixed by removing their dns servers from the dhcp and statically assigning 192.168.1.1 as the dns server in the network-manager. After this the delay was absent. May be I could have used some other free dns server.
Now I tried to see if there was stronger signal available elsewhere in the house. I saw that in the living room near the window I get moderate strength signal (indicator yellow) and the signal strength is -72dBm and SNR around 21 ( RSSI:-72 , CINR:21 ). The speed test was showing consistently above 5Mb/s and, above 0.5 Mb/s upload. Speed was on the average 6Mb/s download and 0.75 Mb/s upload. Sometimes I saw download as high as 7Mb/s. So their claim of 6Mb/s download and 1Mb/s upload is reasonable.
Further tests to see the signal strength outside was hampered by the wifi signal getting weak and causing the wifi connection break. I later saw that the configuration page allows three different power levels for the wifi (short, medium and long) and the default is short.
I am yet to test outside with the highest wifi power level.
I also saw that when I put the iSpot inside the metal can of Pirouette (Pepperidge farm) with the side closer to the indicator lights facing the opening at a distance about 2 inches from it, and oriented the can towards a window the wimax signal strength improved by as much as 5 dB. One thing I later verified was that the wimax antenna on the iSpot is near the end closer to the indicator lights.
I am overall happy with the device. I have to find a way to change the MAC address of the broadcom wifi to be able to use with the laptop without using the external wifi adapter.
Inside the unit
Having seen that the device is working as expected, I decided to open it up and see the internals.
It uses the IC Atheros AR2317-AC1A may be for the wifi. The half elliptical shape antenna around the side close to the indicators. By touching it and seeing that the wimax signal strength goes down (I can't resist a hello to iphone 4 which has the antenna exposed and prone to touch) I presume that it is the wimax antenna.
I can see a miniature rf cable and connector which I guess is for the wifi antenna which I am not able to locate. Touching the connector causes decrease of the wifi signal strength reported by the wifi adapter. The wifi antenna may be on the underside of the pcb which I didn't remove to be able to see.
One can technically use the iSpot to serve any number of devices without spoofing the MAC address of each individual device. This can be done by using a wireless router like asus rt-n12 loaded with DD-WRT, configured as a client bridge whose wireless MAC address is suitably assigned to pass the check of the iSpot. Now the internet connection will be available at each of the ethernet ports of the client bridge. To one of those ports, if one so wishes, can a regular wifi router be attached to serve any wireless device without worrying about the MAC address restriction. iSpot sees only the MAC address of the DD-WRT client bridge.
But I want to mention that it may be against the terms and conditions of the service.
I believe that the iSpot is a rebranded imw-c600w manufactured by the company infomark ( http://www.infomark.co.kr/ ) .
A NOTE: The intent of this experiment is purely educational. I do not suggest anybody do this, nor do I imply the propriety or legality of it. If you use the iSpot service with unauthorized devices it may constitute a breach of the service agreement.
Also see:
http://www.zatznotfunny.com/2010-08/more-ispot-speeds-mac-spoofing/
Sometime back I sold the ispot on ebay.
Monday, July 6, 2009
Switching display resolution for hdtv watching
While watching tv using the hdtv usb tuner mentioned in my previous posts, I noticed that some programs which have a native resolution of 720p come in a smaller box in the middle of the screen.
On the other hand the programs with 1080i native resolution comes beautifully to fill the screen.
I figured out that if use the nvidia-settings interface of my Nvidia gpu and and set panning to 1552x964 in 'X server Display Configuration'-> 'Advanced', my whole desktop becomes of resolution 1552x964 of which only the 1152x864 (the original resolution) portion is displayed on my screen. The hidden portion can be revealed by moving the mouse. Thus using the mouse I could position the 720p video to fill the screen. Nice.
Now the question is how to make the switch easy using command-line.
We are in luck.
Go to ftp://download.nvidia.com/XFree86/nvidia-settings/ and downloaded
nvidia-settings-185.18.14.tar.gz
sudo apt-get install libxxf86vm-dev ( dependency to make nvidia-settings)
tar zxvf nvidia-settings-185.18.14.tar.gz
make
cd samples
make
sudo cp nv-control-dpy /usr/local/bin
nv-control-dpy --add-metamode "1152x864_75 @1552x964 +0+0"
This adds the necessary meta mode to the Nvidia card.
nv-control-dpy --print-metamodes
This prints out the current metamodes. Note down the id of the added metamode.
In my case it was 107. Nvidia uses the frame-rate to store the id.
xrandr --output default --mode 1552x964 --rate id
will switch to the required screen mode and resolution. Replace the id with the actual id noted in the previouse step (107 for me).
To go back note down the metamode id of the original resolution and call xrandr again
xrandr --output default --mode 1152x864 --rate id
Some scripts with more functionality and more details are available here
http://ubuntuforums.org/showthread.php?t=922956
Happy watching.
Arun
On the other hand the programs with 1080i native resolution comes beautifully to fill the screen.
I figured out that if use the nvidia-settings interface of my Nvidia gpu and and set panning to 1552x964 in 'X server Display Configuration'-> 'Advanced', my whole desktop becomes of resolution 1552x964 of which only the 1152x864 (the original resolution) portion is displayed on my screen. The hidden portion can be revealed by moving the mouse. Thus using the mouse I could position the 720p video to fill the screen. Nice.
Now the question is how to make the switch easy using command-line.
We are in luck.
Go to ftp://download.nvidia.com/XFree86/nvidia-settings/ and downloaded
nvidia-settings-185.18.14.tar.gz
sudo apt-get install libxxf86vm-dev ( dependency to make nvidia-settings)
tar zxvf nvidia-settings-185.18.14.tar.gz
make
cd samples
make
sudo cp nv-control-dpy /usr/local/bin
nv-control-dpy --add-metamode "1152x864_75 @1552x964 +0+0"
This adds the necessary meta mode to the Nvidia card.
nv-control-dpy --print-metamodes
This prints out the current metamodes. Note down the id of the added metamode.
In my case it was 107. Nvidia uses the frame-rate to store the id.
xrandr --output default --mode 1552x964 --rate id
will switch to the required screen mode and resolution. Replace the id with the actual id noted in the previouse step (107 for me).
To go back note down the metamode id of the original resolution and call xrandr again
xrandr --output default --mode 1152x864 --rate id
Some scripts with more functionality and more details are available here
http://ubuntuforums.org/showthread.php?t=922956
Happy watching.
Arun
Sunday, July 5, 2009
AverMedia AverTV Hybrid Volar Max (H826D)
I bought an AverMedia usb tuner stick. It works really well in Ubuntu 9.04 with the driver provided on their web site. I get above 30 digital channels with an external antenna. I am 10 miles from DC. After enjoying some crisp HD pictures (1080i) and the 5.1 digital surround audio free over the air (OTA) what better thing to do than to open it up and see what is inside?
Here it goes.
The pictures are taken at night, so excuse the quality.
The main chips used are:
LGDT3304 - ATSC (digital tv) decoder
NXP TDA18271HDC2 - tuner
SAA7136E/1/G - analog demodulator
CY7C68013A - usb driver, 8051 microcontroller
Here it goes.
The pictures are taken at night, so excuse the quality.
LGDT3304 - ATSC (digital tv) decoder
NXP TDA18271HDC2 - tuner
SAA7136E/1/G - analog demodulator
CY7C68013A - usb driver, 8051 microcontroller
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