[digitalradio] Re:You Have Mail Re: How Can We Push HF Emcomm Messages to the Field?
We have started to play around with PSK-31 on HF (40 and 10 meters) for local back-up to our 2 meter repeater. Anybody else doing this? /paul W3FIS Slower Lower Delaware
[digitalradio] You Have Mail Re: How Can We Push HF Emcomm Messages to the Field?
Bonnie, Here is my experience with mobile messaging with Pskmail. This was done on HF NVIS but I believe the concepts are independent of the radio link method (HF or VHF). My background is four wheel driving in the Australian Outback and keeping a track log of my position a well as exchanging email/sms messages where there is no cellular coverage (we have a very low population density and therefore patchy coverage outside the coast and main roads). 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). 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. Note that this is different to connecting to a base like for email retrieval as there is no maintenance of the link through continuous exchanges and therefore very little time occupancy of the channel. It therefore allows for several stations to share the same frequency. How many has not been tested in practice. At the moment the operator has to determine which base to link-to, but a more automated feature coud be used there: with Pskmail the clients can send an automatic beacon every x minutes (to all servers) with the position of the mobile unit. Coordinated over the APRS network only ONE server will reply with a QSL message. The improvement on the current concept could be that the replying server could automatically become the linked-to server pushing messages from there on. So if propagation/conditions change and another server becomes the best link, then it should take over the message pushing task until further notice. I imagine that sending the position from the mobile as a beacon is also valuable in emergency situation as an information to the central command/other mobiles. Another improvement on the current method would be to loosely verify the delivery of the messages. If the server, through the central database were to keep track of the number of messages which should have been delivered, and the client the number of messages received (or the sequence number of the last contiguous messages received), and both client and server exchange this information during the beacon calls, then is is possible to know if the client has all of the messages up to date or not. Messages are packaged with a data integrity information (CRC) and therefore can be determined to be received correctly or not which of course you already have in the HFN system. Great system by the way. A separate point, but relevant in my opinion and was touched on in a previous post: the terminal unit needs to be frugal on power. Even my small eee laptop consumes over 2 AMPs of my 12V supply. If stationary for an extended time, and if not equipped with a separate dual battery system I would be reluctant to leave it on all the time. Maybe something like the a TNC as mentioned before or a software adaptation of the NUEPSK could provide a power budget more in line with a standard battery installation. Rein could give you more details (or correct my understanding) on Pskmail and the new developments. Hope this helps. All the best, 73, John (VK2ETA)
[digitalradio] You Have Mail Re: How Can We Push Emcomm Messages to the Field?
Could you comment further on your experiences with RFSM? 73, Rick, KV9U My local MARS group has been experimenting with RFSM8000. Like MIXW, it is made in Russia, and the author wants to earn some money selling it. Free trial licenses are available. RFSM8000 uses the Mil-Spec modem - I forgot the modem number - but it is the same one used by MARS/ALE. It is supposed to reach 8000bps under good conditions on HF. I typically experience under 600bps. Some say its techniques to get high speed make it illegal for US Hams. European HAMs are using it. MARS does not use the HAM bands, so its OK for MARS. Just because MARS is experimenting with it, does not mean it is adapted by MARS or that it is even a desirable mode. MARS plays with everything and seems to like having almost every tool in their tool-box. MARS even has CW nets. RFSM8000 has three functions: 1. keyboarding NETs - somewhat similar to PSK31. Since we have PSk31, MT63, OLIVIA, and other modes that give similar functionality. 2. file transfers from one user to another user. Most think EasyPal is better. Maybe when we get further along in the sunspot cycle, RFSM8000 will achieve higher speeds and be the file x-fer method of choice? I don't know - time will tell. 3. Email Server. This is the most interesting function. Let's say a disaster area has no internet and can reach an RFSM8000 email server which has internet capability. Then those without internet can connect (one at a time - similar to a winlink RMS) to send and receive email. The Email server sends all users emails using the single server's email address. The subject will start with the originator's call-sign. When the recipient of the email hits reply, he needs to remove the Re: from the subject so the subject starts with the call-sign. The reply email goes back to the email-server's email address, and is routed to the appropriate user's mailbox for pickup by that callsign over HF radio. The simplicity of this compared to Winlink is that there are no CMS email servers that it needs to reach. It is not a huge email system. All that needs to be reachable on the internet is the SMTP server of the ISP the email server is using, and the POP3 server the email server is using. The POP3 server can be ISP's email, or some other email, like gmail, gmx, or any other free email service on the web which uses POP3. Currently RFSM8000 can not make SECURED pop3 connections, and many email systems on the internet do not allow unsecured pop3 connections. So this limits one as to which free emails one can use. Whether the RFSM8000 email server has internet or not, RFSM8000 users can send mail to CALLSIGNS which connect via HF to the RFSM8000 email server. MARS preferred message handling system is WINLINK. If Winlink is broken or unreachable this can be an option. However, it is not clear to me what kind of disaster would make Winlink unusable. Now, on my computer, I have a solution for how to connect to a SECURED pop3 email provider. I have hmailserver running on my computer - it is a SMTP and POP3 email server. RFSM8000 checks its email by going to localhost POP3 unsecured. The hmailserver routinely sucks in mail into the account from a secured POP3 email server - such as COMCAST's POP3 email server. hmailserver can use secured and unsecured pop3 email servers on the internet, and can accept secured and unsecured pop3 connections. But, it may be a bit much for the average ham to install and configure. So the initial lure is 8000bps file transfers and 8000bps email transfers. We are not seeing such high speeds under current NVIS conditions. Howard
Re: [digitalradio] You Have Mail Re: How Can We Push Emcomm Messages to the Field?
Howard, Appreciate your comments on RFSM. Not many have tried it. I have found the speed to be very similar to what you have been experiencing. Even with my experimental set up here in the shack with two computers/two rigs, it does not often get much above 1000 bps with a perfect path. This is using the RFSM2400 freeware program. The RFSM8000 product seems to be more oriented to the higher speeds, but does not meet the slower MIL-STD-188-110A 75 bps very robust mode. Which is a shame, since the most robust modes are necessary to have something that can compete with similar modes such as Pactor. While you can not legally use MIL-STD-188-110A single tone modems in the MF/HF U.S. RTTY/Data portions of the bands, there does not seem to be any restriction in the phone/image portions. I have asked FCC for an interpretation of this but they simply will not respond. Yes, MARS has gone back to having CW nets. That was quite a reversal for them since they prohibited CW for a number of years. I did not realize that you can do keyboarding with RFSM. Maybe this is only possible with the newer RFSM8000 product? In fact that seemed like a significant limitation with RFSM2400. You could easily do ARQ file transfers, and the stations would constantly be testing back and forth, waiting for the next message but I did not see any way to get a keyboard type window open unless I completely missed it. The server feature is quite interesting, sounds similar to the PSKmail server, which is an ad hoc approach without the incredibly complications of Winlink 2000's system, however, you give up some of the convenience features. It sounds like you have considerable expertise with setting up such a system to e-mail access. At this time it is still a moot point for HF since you can not use for HF text messaging as mentioned above. Of course, it is completely legal to use on 6 meters and up which allows for much higher baud rates than the quasi 2400 baud rate of the MIL-STD-188-110A modems. I wonder if this would have any possible use for providing localized connectivity for VHF? 73, Rick, KV9U Howard Z. wrote: My local MARS group has been experimenting with RFSM8000. Like MIXW, it is made in Russia, and the author wants to earn some money selling it. Free trial licenses are available. RFSM8000 uses the Mil-Spec modem - I forgot the modem number - but it is the same one used by MARS/ALE. It is supposed to reach 8000bps under good conditions on HF. I typically experience under 600bps. Some say its techniques to get high speed make it illegal for US Hams. European HAMs are using it. MARS does not use the HAM bands, so its OK for MARS. Just because MARS is experimenting with it, does not mean it is adapted by MARS or that it is even a desirable mode. MARS plays with everything and seems to like having almost every tool in their tool-box. MARS even has CW nets. RFSM8000 has three functions: 1. keyboarding NETs - somewhat similar to PSK31. Since we have PSk31, MT63, OLIVIA, and other modes that give similar functionality. 2. file transfers from one user to another user. Most think EasyPal is better. Maybe when we get further along in the sunspot cycle, RFSM8000 will achieve higher speeds and be the file x-fer method of choice? I don't know - time will tell. 3. Email Server. This is the most interesting function. Let's say a disaster area has no internet and can reach an RFSM8000 email server which has internet capability. Then those without internet can connect (one at a time - similar to a winlink RMS) to send and receive email. The Email server sends all users emails using the single server's email address. The subject will start with the originator's call-sign. When the recipient of the email hits reply, he needs to remove the Re: from the subject so the subject starts with the call-sign. The reply email goes back to the email-server's email address, and is routed to the appropriate user's mailbox for pickup by that callsign over HF radio. The simplicity of this compared to Winlink is that there are no CMS email servers that it needs to reach. It is not a huge email system. All that needs to be reachable on the internet is the SMTP server of the ISP the email server is using, and the POP3 server the email server is using. The POP3 server can be ISP's email, or some other email, like gmail, gmx, or any other free email service on the web which uses POP3. Currently RFSM8000 can not make SECURED pop3 connections, and many email systems on the internet do not allow unsecured pop3 connections. So this limits one as to which free emails one can use. Whether the RFSM8000 email server has internet or not, RFSM8000 users can send mail to CALLSIGNS which connect via HF to the RFSM8000 email server. MARS preferred message handling system is WINLINK. If Winlink is broken or unreachable this can be an
Re: [digitalradio] You Have Mail Re: How Can We Push Emcomm Messages to the Field?
Rick, we are doing a bit better on speeds with RFSM8000. We sometimes get up to 3200. Maybe it depends on the bandwidth available. I open my transmitter to 3 kHz and my receiver even wider. Have not tried on FM / VHF yet but hope to do that soon. Even at 600 or 1200 it is so much faster than the alternatives that nothing compares to it. I don't have an SCS modem so that is not an alternative to me. This is valuable when sending messages or files. We had bad band conditions this evening and I was able to receive a 29k spreadsheet in 11 minutes and 40 seconds. The Broadcast feature of the RFSM8000 version allows you to chat without being connected. This could be used to run a net. Howard Brown (The other Howard) From: Rick W [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, December 2, 2008 10:58:12 PM Subject: Re: [digitalradio] You Have Mail Re: How Can We Push Emcomm Messages to the Field? Howard, Appreciate your comments on RFSM. Not many have tried it. I have found the speed to be very similar to what you have been experiencing. Even with my experimental set up here in the shack with two computers/two rigs, it does not often get much above 1000 bps with a perfect path. This is using the RFSM2400 freeware program. The RFSM8000 product seems to be more oriented to the higher speeds, but does not meet the slower MIL-STD-188- 110A 75 bps very robust mode. Which is a shame, since the most robust modes are necessary to have something that can compete with similar modes such as Pactor. While you can not legally use MIL-STD-188- 110A single tone modems in the MF/HF U.S. RTTY/Data portions of the bands, there does not seem to be any restriction in the phone/image portions. I have asked FCC for an interpretation of this but they simply will not respond. Yes, MARS has gone back to having CW nets. That was quite a reversal for them since they prohibited CW for a number of years. I did not realize that you can do keyboarding with RFSM. Maybe this is only possible with the newer RFSM8000 product? In fact that seemed like a significant limitation with RFSM2400. You could easily do ARQ file transfers, and the stations would constantly be testing back and forth, waiting for the next message but I did not see any way to get a keyboard type window open unless I completely missed it. The server feature is quite interesting, sounds similar to the PSKmail server, which is an ad hoc approach without the incredibly complications of Winlink 2000's system, however, you give up some of the convenience features. It sounds like you have considerable expertise with setting up such a system to e-mail access. At this time it is still a moot point for HF since you can not use for HF text messaging as mentioned above. Of course, it is completely legal to use on 6 meters and up which allows for much higher baud rates than the quasi 2400 baud rate of the MIL-STD-188- 110A modems. I wonder if this would have any possible use for providing localized connectivity for VHF? 73, Rick, KV9U
[digitalradio] Emcomm Message Notification Routing Networking Re: Push Messages to the Field
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? 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? 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. 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. 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. 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. 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. 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 :) 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. 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). 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.
