O.k., needed some time getting internet back up, ISP change during my trip :)
> > Hi John,
> > Thanks very much, for the detailed comments on
> > PSKmail for this type of application. That is the
> > probably the closest I've seen to approaching
> > "push message" capability.
> > Here's some follow-up questions:
> > How does the mobile operator determine which
> > PSKmail base and frequency to check in to
> > at any particular moment? Is it manually
> > selected by the operator, i.e., does the mobile
> > operator need to keep manually checking if they
> > remain "linked-to-base" on an ongoing basis?
(Talking EU situation, which is the most mature)
Every band has a preferred pskmail APRS frequyency with several
servers operating that are geographically spread. E.g. on 10148.0 we
have IS0GRB-3, PI4TUE, DK4XI-0, SM0RWO, S54FAA-4.
The operator can choose the best server 2 ways:
* The mobile station hits the ping button and the servers ack the ping
* The mobile station automatically sends a posit beacon and the servers
QSL the position
Choice is manual by the operator.
This is not necessary for SENDING APRS messages targeted to a callsign or
for single line emails to an internet address. All servers receiving the message intact will act.
To SEND these types of messages a link is NOT necessary.
To RECEIVE an APRS message on HF which is targeted to your callsign you need to be LINKED to a server.
This link concept has been introduced because pskmail uses the APRS backbone system to
deliver ist messages. All APRS messages directed to PSKAPRS are transmitted to HF, provided the
targeted callsign is in the link table of the server. This concept prevents more than one (or
ALL) servers to send the message, clobbering up the bands..... So only one server sends the message.
This is fully APRS compatible. So a station on 30m pskmail can send a message to
VK2ETA on 2 meters, or, on the internet with e.g. UIview.
Only one server can own the link, upon linkup the server sends a 'GATING VK2ETA' message via
APRS and all other servers drop the linked station form their table.
This works both ways, so you can send APRS messages to a pskmail station from any APRS node.
In the client, sending a message is as easy as writing 'KX6QA this is your message....',
Messages will be shown in a 'incoming messages' window.
The end-to-end acknowledgement of the APRS messages (numbered) has been implemented,
but the operator has to manually resend if the ack does not come. Again, to prevent
endless unnecessary transmissions on HF!
The EMERGENCY button in the client opens a special dialog to send an APRS messages to ANY with
the special EMERGENCY Icon.
> > Does the op need to keep finding another base
> > to be linked-to-base" with, so that the notification
> > messages get routed properly? What is the fall-back
> > position for the system for notification, in the
> > case that none of the bases show a link-to-base
> > condition when the target mobile op hasn't checked in
> > for a while? Is there a time-out or "not-linked"
> > indication to the network or mobile op?
No. But the footprint on HF is HUGE, and the half-intelligent OP will
learn quickly which server suits him best onm that time of day.
All messages are stored at findu.com.
As soon as the station is activated, it can check in by choosing any
workable server and pushing the GDET MESSAGES button.
Pskmail will connect the server and get the last 10 messages from the
relevant findu web page and send them to the client.
> > I'm very interested in the network server side of
> > how this can work smoothly. I think that it is the
> > key to getting the best notification system. It
> > would make sense to join as many ham networks as
> > possible to this, to enable a message to be routed
> > to the target operator by any method they are using.
> > A mutual cooperation between ham networks could
> > be forged, and this could make it a reality.
Well, JOIN THE CLUB!!
I have chosen pskmail to be 100% compatible with the
existing APRS network, no more specification to be done, just
> > If one dials a telephone number, it isn't necessary
> > to know which telephone provider company that the
> > called party is using. We need to carry this type
> > of universal networking into the ham radio realm.
> > The "email address" provides universal portability
> > and networking opportunities for hams. Hams could
> > adopt specific email addresses that are used for
> > emcomm purposes, and use email forwarding. This
> > simple feature could be leveraged to provide
> > powerful networking for hams.
There is also the possibility to send email messages to ANY internet
email address. Simply write 'Bonnie@...
This is your message'.
Any server receiving the packet intact will send the email via smtp
(if the smtp agent has been configured correctly).
For this the server needs to know the sender's return address, otherwise
it will refuse to send the email.
Special email addresses can be generated via gmail. E.g I use PA0R at RRDXA.eu, or
PA0R at pskmail.de
Sop an address like PA0R at hsmnetwork.net is easy to organize.
> > At least for the HFN system, the high probability
> > of linking on HF has already been achieved through
> > the power of a network of geographically distributed
> > HF base stations running simultaneously on all bands.
PSKmail is also using this concept for messaging. And no necessaty to connect,
just send the message for any of the servers to pick up.
> > It has often been pointed out that HF base-to-mobile
> > can be statistically undependable for 24/7 point-to-point
> > communications with a base station, due to the changing
> > ionospheric propagation and channel conditions.
PSKmail servers can scan 5 frequencies per 5 minutes,
> > However, the statistical probability for successful
> > communications with a mobile goes way up when
> > dynamic linking with any base in a geographically
> > distributed HF network is added.
I chose to make pskmail as much operator driven as possible,
because of the problems with pactor.
> > A single ham band may not be open at any given
> > instant between 2 specific stations.
> > In fact, there might not be any HF band open between
> > those 2 specific stations :)
That is why pskmail always uses the internet as a lin king device,
so stations can be on completely different bands to send messages.
Even stations with only ingternet APRS can take part in the network.
> > But, it is very rare that all HF bands are closed to
> > everywhere.
> > That points to the need to develop a wider, more
> > flexible, network outlook for HF Emcomm systems;
> > one that is not concentrated so much on NVIS or
> > specific regular propagation patterns.
> > The solar flare that happened during the Katrina
> > disaster response certainly taught us how fragile
> > traditional Net-Control-centric state nets can be
> > that rely on 75 meters only.
There is no reason why pskmail could not also be used on VHF as a
'last mile' technology. And modes like THOR22 give us lots of
possibilities to experiment with bad channels!
> > Bonnie VR2/KQ6XA
> > > John (VK2ETA) wrote:
> > > Bonnie,
> > > The way Pskmail addresses the push messages is by using two concepts:
> > > 1. A notion of Linked-to-a-base status and
> > > 2. a centrally accessible (over the internet)
> > > database so that servers can be coordinated and
> > > avoid duplication).
Actually, the concept of sending basic data to the server via air has shown to be
so succesful that the central database has been killed, to get rid of a
single point of failure. The 'update server' button is your friend here....
> > >
> > > More details: The clients (mobile units) have to
> > > "check in" by sending a "link to base". From there on,
> > > the server will push any new APRS messages
> > > (without ack) to the client. Of course other message
> > > sources could be pushed as well.
As shown above, this is only necessary for the receiving nodes.
Hope this sheds some light on the pskmail messaging system.
Quintescense: 100% APRS compatible, using existing resources.
Join in and expand the network!
Rein PA0R (@home agn)
PS: I did not talk about the capability to send and receive emails and
to receive info via the web here, just the messaging part!