Mt. Whitney 2018 ~ Reservation on April 1

Trail Camp

April 1!!

   Today is April 1 which is a date all non reserved dates is available to public.   I tried to get one of spots.  Since when I checked the availability last night.  I found some spots.   However the site says they cannot be booked until 10:00am (EDT/USA).   Therefore I woke up before 7:00am(PDT) which is 10:00am (EDT).  Then I click the boot button just at 7:00am.   However it was too late and almost all spots are immediately gone except very early / late date like May and October. 

   Wow!!

   Any way I will keep watching the availability and try to get a spot for hiking this year.

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.