APRS ~ the packet is not recognized in some location

APRS stations near Brentwood

(There is one DIGIPEATER on Mt. Diablo)

  After testing APRS a couple different location, it seems that it is hard to send out the packet in some locations.   In my commute route, somewhere between Fremont and San Jose is one of locations.   I also went to Brentwood where might be a similar.
   For the commute route, it does not depends on the output power.  Even if I set the output power higher which is 8W instead of 1W.   I do not see much improvement.   It seems that it is just because more traffic.   From home to Fremont, almost all locations I sent was recognized, but after Fremont, probably a half of sending is missed.   A similar thing happened in Brentwood.   I tried to use 8W in Brentwood, it does not seem to help.   Instead of using higher power, it helped sending more frequently.   Then one out of ten was recognized.  In Brentwood, I did see more packets were going on.   If there is a lot of traffic, I guess using hand held might be some disadvantage.   Many mobile radio or base station might be more power something around 25W to 50W with probably a better antenna.
   It might happen when I use it on a trail.  Even if the location is better, it might be a similar situation.   So I really need to go hiking to try to see if it is still useful or not.   Originally, I thought it can be picked up if a DIGIPETER or IGATE station are reasonably close.  But it does not seems to be. 

Mt. Whitney Lottery 2018 ~ not successful ....

Early in the morning on Mt. Whitney Trail

(Near Trail Crest)

   On March 24th, the result of Mt. Whitney Lottery was announced.   Unfortunately I could not win the lottery this year.  The next step is waiting for April 1 to look for some open spots and May 1, some spots which is not confirmed by the lottery winner will be open to everybody.

   I will try to get a spot for my hiking this year.

APRS - sending SMS message

SMS message from APRS

I was looking for a way to send a text message in the both direction from / to amateur radio.  The one I mentioned in the previous post is one-way communication from an amateur radio to a mobile device via E-mail.   We cannot reply to the message on the mobile device side.   That is a big limitation for the communication.

After I checked the web site of APRS, there is another service through SMSGTE (APRS/SMS Gateway).   This method provides communication in the both direction with some limitation.  I think it works.

Here is how it works:

1. Using "SMSGTE" instead of a call sign when people send a message
2. In a message body, inserting "@xxxxxxxxxxx " (xxxxxxxxxx is a phone number) to specify the destination of SMS message.

As long as the packet is going through to APRS-IS via IGATE station, a message can be delivered to a mobile device.   Also the person who received the message can reply to the message with in 30 minutes from the last message.   I tested this scheme in some different location with disabling cellular network data.  Now this might be a way to send a message even if a cellular network is out of the range.  Now APRS is probably very useful on a trail during hiking.

If you carefully look into the site, the service is provided in limited region.  The United States is one of countries where the service is available.

• We can send out a location information periodically and people can trace the location from the internet.   (To trace the location history, no amateur license is required)
• We can tell stations who is close to the current location.   Call-signs are listed and they can exchange messages each other.  It is probably useful to contact those station in case people needs some assistance.
• We can send SMS message to any mobile device. (limited countries)

To use APRS, people need to get amateur radio license, but I think it worth to get it.   It helps a lot in case something happens during hiking in an area where a cellular service is not available.

APRS ~ Text message

Text message exchange
   APRS is not only tracking a location, but also sending messages.   I have not really test to exchange messages between amateur radio stations listed on the software.   I think as long as the both stations are in a range to communicate each other, it should not be a big problem to exchange the message.   However, I am not really sure if we can send a message from a radio to a station on the internet.  Basically a smart phone software "PocketPacket" can be used with the internet connection.  Therefore I thought I could send a message from radio to such station.   Based on my simple experiments, it does not seems that the message is really going through.

Email from a radio

   However based on an internet search, it is possible to send out an email.  Just using "EMAIL" as receiver.   For the US cellular carrier, it is also possible to send a text message as well.

• Sprint: [insert 10-digit number]@messaging.sprintpcs.com
• T-Mobile: [insert 10-digit number]@tmomail.net
• AT&T: [insert 10-digit number]@txt.att.net
• Verizon: [insert 10-digit number]@vtext.com

The email address is a part of a message body like, "xxxxxxxxxxxx@vtext.com test message"

I tested this method and works, as long as the packet is picked up digipeater / iGate, then the message was delivered.   The problem is the receiver could not reply the message.

I still need to learn how the message could be sent out to a station....

But at least, a text message can be sent even if an area is out of cellular network.  It is still useful.

Mt. Whitney Lottery will be closed less than 24 hours!!

Mt. Whitney Lottery will be closed at midnight on March 15th (Eastern Time/USA).
It is better to rush if you have not filed your application this year!!  Less than 24 hours!

APRS experiments ~ potential concern for low power transmission

Low Power Transmission

   Now I am testing APRS with BAOFENG UV-5R / iPhone.  I found one potential concern during this experiment.  Since I am considering to use APRS during hiking and it will be a long operation during hiking.  It could be more than a several hours.  To save the power, I try lower power.

   From my home, digipeaters near my home can pick up the signal even if I transmitted 1W.  So I started using 1W output power to track during my commute.   It seems that it works well near home, however some packets are not recognized if the location is close to my office.   I saw a couple packets are missed, probably around 50% is not recognized.  (It can recognize packets sent by digipeaters.)

   Here is my best guess.   Since APRS is using the same frequency (channel) to send a packet, it is possible to conflict some packets almost at the same time.  If other stations sending them with higher power / efficient antenna, a weak signal which was sent by lower power / inefficient antenna might be overridden.  This is probably a nature of FM signal and traffic on APRS channel near my office is much more than around my home.

   To understand more, I think I need more data with different power.  I will continue to correct more data to understand this.

Mt. Whitney lottery ~ will be closed on March 15!! ~ Did you submit your application?

From Trail Crest on Mt. Whitney Trail

(North side view)

Mt. Whitney lottery for this summer season will be closed March 15 this week.
All applications need to be submitted by midnight on March 15, 2018 Eastern time.

For detail is on a web, Inyo National Forest page.

Better to rush if you plan to hike there this season!!

APRS ~ Test from home with rubber ducky antenna

   Today, I tested APRS with BAOFENG/iPhone from home in daytime.
   There are two digipeater near my home.  Based on information on "https://aprs.fi", one digipeater is about 5.3 miles from my home and the other is about 16.1 miles from my home.  Since I do not have any base station antenna, therefore I just use the rubber ducky antenna in a room and set the output power as a low power (1W).

   It seems the both digipeaters can pick up my APRS packet and I can see some packets from other station through those digipeaters.  At least it works around my home with low power setup.  Also, today, I did not see any unexpected transmission at all.   I guess some setup yesterday might not be right.

The current setup is:

On PocketPacket:

• VOX trigger is 400msc

Radio:

• VOX setup value on BAOFENG UV-5R is "10"
• The volume is middle position

iPhone:

• Volume setup is the maximum on iPhone

It has been running more than 2 hours and I saw some stations near home.  The next step is trying to use this on a trail.

APRS ~BAOFENG UV-５R with iPhone App "PocketPacket" ~ It works!

APRS setup with iPhone

BTECH APRS-K2 Cable

  I got a cable to connect between BaoFeng UV-5R and iPhone from Amazon.  I tested this configuration today.   It works!  I can send out a packet with a location information to digipeaters and I also can receive from other stations.

  I guess this might be one of low cost solutions to use APRS through amateur radio, not rely on a cellular network.

Here is the configuration:

1. Radio (Transceiver): BaoFeng UV-5RTP
2. TNC modem: iPhone 5 + PocketPacket
3. Cable (between the radio and iPhone); BTECH APRS-K2

   It is not like a solution with all-built-in radio from YAESU and KENWOOD.  However, just thinking about the cost, it is probably OK.  However, it might not be very convenient when I am on a trail.  Since the setup needs to be dedicated for APRS and to do a regular QSO, we need to disconnect everything and using as a regular mode.  Also, I mentioned the previous post, iPhone will consume a lot of power due to GPS.  Therefore, we might need an external battery to feed power to iPhone since GPS function always needs to be enabled.   Those are potential concern.

Other observation

   I saw sometimes the radio transmitting something unexpected.  I do not find out why.   However, I saw a couple times even PocketPacket transmitting is disabled.  When I just connect headset instead of the cable, I could not hear anything.  Therefore, currently I have no idea why the VOX switches to transmit something.   Most of time, it works well and I did not see this symptom.  But it happens sometimes.   I will spend some time why it happens, but currently I do not have any ideas.

APRS with BAOFENG UV-5R ~ I just order a cable from Amazon!

   As an experiment, I confirmed that transmitting a APRS (AX.25) packet and the location shown in a map.   I am looking for a solution to receive packets from the other stations.  The problem is the cable connection between iPhone and the radio.   I do not have any extra cables to get the connectors.

   After some web search, I found a cable on Amazon!!

BTECH APRS-K1 Cable

I just ordered the cable on Amazon and it is expected to deliver on Friday.   Once I get the cable, I will try it and to see if it works or not.

APRS ~ BaoFeng UV-5R + iPhone app "PocketPacket"

Pocket Packet can be used with a 2m radio
   The previous post was talking about two smart phone applications which send the information through cellular network.   During its research, I found some information on the internet that "Pocket Packet" application can be used as TNC (Terminal Node Controller) and BaoFeng can send out the information from audio output from iPhone.  With this solution, it does not depend on the cellular network.   A smart phone is only used to get the GPS or the location information and generating a packet information as the audio output.   No data is going through a cellular network.

Pocket Packet Setup, BaoFeng setup and cable connection

   First of all, disable APRS-IS connection.   As a smart phone application with a cellular network, this function is the path to APRS-IS server.  Width disabling this portion, the application won't send any data to APRS-IS server.   It is also OK to disable "Cellular Data" on iPhone.

Disabling APRS-IS connection

(Turn off "Enabled" and "Transmit")

  Second, enable "Audo Modem" setup on "PocketPacket" setup.  This is a function to create audio output which includes the location information.

Enabled Audio Modem

(Turn on "Enabled" and "Transmit", see the green switches)

  They are the key setting to use a radio to transmit via amateur radio.  Then the last thing is connection between iPhone and a radio (transceiver) .   The article I mentioned above is using a custom hand-made cable for this connection which has a connection from "audio output" to "microphone".

   Since I do not have any extra head set to get connectors on the both end.  I just using a stereo audio cable with 3.5 mm standard jacks on the both side.   I put it to the iPhone ear-phone jack and BaoFeng microphone jack.  Then enable VOX function on the BaoFeng side.

   The frequency for APRS in north America is 144.390 MHz.  In my case, I set iPhone volume as the maximum and set BaoFeng VOX to 5.  Since this is just 1-way connection and no incoming packet is routed to iPhone.  So this is just a test to see if we can send out APRS AX.25 packet through amateur radio.   (My iPhone is an old iPhone5 which has audio jack.  Newer models (after iPhone 7), it is requires to use a short cable to connect audio cable.

   With above setup, it was successful.   I can see my data on aprs.fi.

Trace when I was driving

  It is a good news, we can use iPhone as TNC with most of handheld radio with VOX function.  "PocketPacket" supposes to get incoming packet if we have connection from the radio.  I have not tried this yet.  But I will try it and post the result.

   I guess this might be a good low cost APRS solution through amateur radio!

APRS -- Easy solution ~ iPhone App

   I mentioned about APRS (Automatic Packet Reporting System) a few weeks ago.   I am looking for a solution for my future hiking to trace my location during hiking.   In case something happens to me, it can be a way to help to find out where I am.  That is my motivation to use APRS.

   There are some handheld radios which has built-in APRS features, but the price of the radios are expensive.   For long term, I am considering to get such radio in the future.   However I am looking for something low-cost solution for short term.

iPhone App - "aprs.fi"

   I think one of lowest cost solution is a smart phone application.   There are some applications in AppStore.   My smart phone is an iPhone and I did not search Android apps.   "aprs.fi" is the one which is listed as the first app when I search "APRS" in AppStore.   It is USD $6.99.   It is an application on an iPhone to send the location information through cellular network, not through amateur radio.   Therefore, it won't work if a location is not covered by a cellular network.  It is different from one going through amateur radio.   Even though, it is still useful to use in local trails where majority of trails are still covered by a cellular network.

   There is a limitation that the location information is not really report to APRS-IS servers.  Therefore if people is not using the application or "https://aprs.fi" site.  The location information is not shown on the other application for APRS.   As long as people use those application, it is not a problem.   The setup is easy and this is probably an easy solution for most of local trails.  Since this is using a cellular network and utilize its data plan.  I think each data size is not really big, however if the interval to send the location information is short and long hiking, it will use some amount of data. 

Another App - "PocketPacket"

   Another iPhone application I tried is "PocketPacket" which is USD $4.99.   I think this application would be lower cost and better.   The setup is a little more than "aprs.fi".  However this application sends the location information to APRS-IS servers and any application can see the location.   So this is less limitation.   However, to send the information APRS-IS servers, it might requires "passcode".  (I am not really sure, but I think I get error without the passcode.)

   I just did an internet search and a site can generate a pass code with a call-sign.  The URL of the site is "apps.magicbug.co.uk".   I found it by a Google search with "APRS passcode".

The next post will talk about a way to send the location information through amateur radio!

Mt. Whitney Lottery will be end MARCH 15!!

From the visitor center in Lone Pine

   It is March now.   There was not much snow this winter, however, last wee and this week, we are getting big snow in mountains.  

   I just mentioned about Mt. Whitney Lottery this year about 2 weeks ago and I filed it.   This is a soft reminder people who have not filed.  The lottery will be end on March 15 midnight in eastern time.   It is better to rush to file it if you plan / want to hike Mt. Whitney this year.

  Please also check a kindle books about Mt. Whitney as well.  (The link is Amazon.com, and you may want to check your local Amazon site, it is probably available as well)

Mobile antenna installation - NAGOYA UT-72

NAGOYA UT-72

   It's been for a month after I bought BAOFENG UV-5R.   I've been listening (watching) 2m / 70cm bands during my commute.   However, "rubber ducky" antenna is probably not really good especially using inside a car.   Therefore, I was looking for an external antenna to improve it.

   Since I do not have a nice mobile transceiver and I am just using the cheap handheld radio, I do not want to have really nice mobile installation.   I just looked for an easy way.  I also have another car which is primary used by my wife.  So I just want to have one which is easy to move one to the other.   When I search on Amazon, there are some cheap one starting from a little above USD $10.   Based on the review, it seems to be really cheap and I just pick one with a little more cost.   It is still under USD $ 30.

   Here is what I picked.   "NAGOYA UT-72"

   Based on the description on Amazon, the height is about 19-inches and getting more than 4 dB gain.  The magnet base is 3.25 inch and it is stable enough even I drive on a free way.  Installation is pretty simple, just put it on the roof and routed the coax through a gap around a door.   The end of coax is PL259 and a jumper cable to convert to SMA female (the radio side is SMA male, which is different from a common connector of major Japanese manufactures).   Therefore, it can be used when I buy a mobile radio in the future.

   It is hard to quantify the performance, but obviously it is improved.   I can hit more repeaters from my home and office.   Also, the reception is getting much better.   Just think about the price, I am happy with this antenna.   Currently, I do not have any base station antenna at home.  Probably, I also want to have an antenna at home as well.