Some people will tell you that APCO-25 is the regulatory standard for mandatory compliance with new FCC narrow band rules. That isn't exactly correct.......
You've heard the rumors. All public safety agencies must purchase APCO-25 (P25) 2-way radios to receive federal funds because the Department of Homeland Security (DHS) guidelines state that all new radio purchases should be APCO-25 compliant. More recently, FEMA stated that only P25 radios would be considered eligible for funding for those applying for Assistance to Firefighter grants. There is also the issue of FCC compliance, compliance with state interoperability plans and a maze of alternatives presented by prospective suppliers. We thought maybe a little straight talk was in order. Let's start with an overview of APCO.
An Introduction to The Associated Public-Safety Communications Officials (APCO)
Originally an association of police communications technicians, APCO has grown into a PRIVATE ORGANIZATION that provides a number of services relating to government communications. Notably, APCO is one of several frequency coordinators responsible for coordinating frequency assignments before an application is filed with the Federal Communications Commission (FCC). APCO also has a technical standards group responsible for planning the future needs of police (and more recently public-safety) users. It was through this group that a standard for advanced narrow band communications was developed. For now, let us say that the basic objective of the P25 operating standard is to provide an efficient migration plan from analog to digital communications. Additional information on P25 is available at www.apco911.org/frequency/project25/information.html.
This standard is known as APCO Project 25, APCO-25, or simply P25. The first step development of a common operating standard. It is called a Common Air Interface (CAI), which in layman's terms means that P25 radios from different manufacturers should be able to talk to each other. Further, APCO-25 defines a standard for migrating from the current bandwidth of 25 kHz to a reduced bandwidth of 12.5 kHz (this is known as narrow band) using FDMA digital technology in Phase 1 and TDMA in Phase 2 (more about this later).
The original Phase 1 radios are designed to operate on either 25 or 12.5 kHz channels in an analog or digital operating mode. For lack of a better term, we call these Phase 1 conventional radios.
As federal government agencies were required to purchase only P25 compliant radios, some of those agencies (notably the U.S. Forest Service and other "outdoor usage" agencies) asked for features that could be borrowed from military versions of P25 radios. These users included Over The Air Programming (OTAR) and encryption (scrambler to our non-technical readers). There are two levels of encryption - Digital Encryption System (DES), the original and least expensive type, followed by Advanced Encryption System (AES) which is VERY expensive but more secure than DES.
Basic Phase 1 P25 radios such as the ICOM F70/80 portables or Motorola PM1500 mobiles are conventional analog radios that can be upgraded to digital operation. Technically, at least by the interpretation of many experts, these radios are P25 Phase 1 compliant. We leave the final decision on this subject to the individual user and those who extend grant money. However, we are of the opinion that the standard defines a DIGITAL radio using FDMA technology that has BACKWARDS compatibility with analog radios operating at 25 or 12.5 kHz channels spacing in a mixed mode of operation.
The FCC originally proposed a requirement for all radios to operate on 6.25 kHz channels by 2018 with 25 kHz operation phased out by 2013. By FCC mandate, all radios built in the USA must be capable of operating at 6.25 kHz after January 1, 2011. The P25 standard incorporates this provision as Phase II.
On the assumption that analog radios will not operate efficiently at 6.25 kHz (Very Narrow Band), the APCO-25 project defined a new radio standard that would allow APCO-25 radios to operate on 12.5 kHz in either an analog or digital mode as well as 6.25 kHz digital only mode using TDMA technology (more about this shortly). The Phase 2 operational standard for 6.25 kHz will include backwards compatibility with Phase 1 digital as well as analog operating modes. It should be again noted that APCO is NOT a government agency and has no regulatory authority over any user - either public safety or private. APCO-25 is simply an evolving standard that has been endorsed by a number of manufacturers and users, in particular in the public safety sector.
Currently (November 2009), P25 is one of only two digital technologies offered in the USA offering repeaters with backwards compatibility to analog systems, and a migration plan for updating to true 6.25 kHz channel spacing. The other system is called NXDN, a joint development of ICOM and Kenwood and endorsed by a number of other manufacturers. At this point, things get a little confusing.
The Common Air Interface (CAI) provided a good interoperability solution for Phase 1 portable and mobile radios. Unfortunately, the door was left open on repeaters (both conventional single channel and trunked multi-channel types). This oversight allowed repeater station manufacturers to build system with enhanced networks offering features above and beyond the original P25 requirements. The advancement of Internet Protocol (IP) coding provided yet another distinction between enhanced infrastructure versus traditional P25 technology. Literally translated, this means that all P25 radios are NOT compatible on all repeater systems. The race was now on - for those with proprietary technology to stay ahead of the pack so they could sell more portables and portables with freedom from competition versus those trying to catch up. That is why, for example, manufacturers such as ICOM have two different series of P25 radios. Then, things got even more confusing......
In the fourth quarter of 2009, Motorola announced the development of what appears to be the first tri-band (VHF-UHF-700/800 MHz) radio based on TDMA technology (the APX7000 portable and APX7500 mobile). The race began with many manufacturers rushing to offer a similar product with the charge being led by Harris, Johnson, Tait, and undoubtedly others. By mid 2010, multiple manufacturers will be certified to offer equipment compatible with this new standard. Even though, this will provide some degree of competition, the prices will typically be TWICE as much, or even more than Phase 1 P25 equipment. This evokes the need for a comment.
Phase 1 P25 uses the FDMA modulation technique, the same as used by NXDN equipment suppliers. FDMA has proven to be efficient and affordable but Phase II P25 uses TDMA. Why the change? First, let's review the differences between FDMA, TDMA, and CDMA (the system most commonly used in Europe). All of these systems were primarily developed for cellular use. Go to www.info4u.us/differences.pdf for a basic review of the technical differences in each protocol.
That didn't give you much of an answer did it? But, you now know the technical differences. Now, lets look at the practical consideration of this upgrade. Both FDMA and TDMA are old cellular protocols known as 2G (Today's networks are mostly based on 3G technology). Fundamentally, 2G networks were designed primarily to handle VOICE communications. 3G networks were designed to be more efficient for handling DATA communications (text messaging, GPS, music, video, and even VoIP). However, the rest of the world demands higher speeds. 2G rolls along at 9.6 Kilobits (think 1980), 3 G is roughly comparable to DSL (128 Kilobits to 3 Megabits for typical residential service). 4G performs at 100 Megabits or better! You can get better cellular phone service in Pakistan than in the USA as 4G is in use there TODAY!
So the question is, why would you ignore the superiority of cellular technology, both in terms of cost and efficiency when developing a new 2-way radio standard? The fact is that a 2-way radio is nothing more than a cellular RADIO less the phone dialing capability and nation/world wide network and the world wide network is nothing more than a great big VoIP (Voice over IP) system. Instead, our "latest" technology for public safety radio uses communications technology that is basically obsolete coupled with exorbitantly expensive infrastructure. For most of us, P25 Phase 1 is a far more efficient and affordable alternative to P25 Phase II. There is no date certain established by the FCC for mandatory conversion to 6.25 kHz so the immediate need to convert to 6.25 kHz isn't a major consideration. As far as Tri-Band radios are concerned, the Amateur (Ham) radio operators have used such devices for years with a cost of about a tenth that of the "new" Phase II technology offerings. So now the question is, as a user, what do YOU do?
Well, we can't go to 4G. The massive standoff between Google and the major cellular network providers (among others) debating the superiority of LTE versus WiMAX retards the building out of an efficient broadband network. Meanwhile, the rest of us have to live in the world that is. For those unfamiliar with the difference between LTE and WiMAX, let us just say for now that APCO appears to favor LTE while the rest of the world with the exception of AT&T and Verizon favor WiMAX. Additional information is available at http://gigaom.com/2008/03/05/a-little-4g-sibling-rivalry. Now, back to what to do about P25 (whatever that is.....).
First, let's address Tri-Band radios which we need like a hole in the head. Here's why! Let's assume a cost of $5,000 per radio for an agency user with 25 portable radio users. That equates to $125,000 and that doesn't include infrastructure. Instead, let's assume the purchase of three radios, one each for VHF, UHF, and 700 MHz at a typical cost of $2,000 each connected to a SafetyNet Quad interoperable bridge at $10,000 (more about this shortly) which can provide all users of SINGLE BAND radios with the ability to talk on all three networks. That comes to a total of $16,000. Now we purchase 25 P25 Phase 1 portables at $2,000 each for a total of $50,000. $16,000 plus $50,000 equals $66,000 which is roughly HALF the cost of purchasing P25 Phase II portables and we haven't even discussed hidden monthly fees normally associated with 700 MHz systems or the significant benefits of using an interoperable bridge!While we are on the subject of planning and frequencies, and interoperability, we would like to share a few reference sites which we think you will find to be of interest. First, let's start with the subject of whether the 700/800 MHz band is "better" than VHF or UHF. If you would like a little clarification on this subject, please visit http://falconinfo.blogspot.com/2009/11/vhf-versus-800-mhz-real-facts.html. If you would like more information about the REAL requirements for converting to narrow band operation, please visit www.info4u.us/Narrowband_FAQs.pdf.
If you would like more information on interoperable planning between 700/800 MHz and VHF or UHF systems, we have a special report at www.info4u.us/MigrationPlan.pdf. We think it will answer a lot of questions for you and if you would like more information on our interoperability solutions, please visit www.info4u.us/Extender.pdf.
We hope you now know more about the many facets of P25, narrow banding, and interoperability. We should point out that we are not members of IEEE, APCO, any agency of the federal government or in any way any smarter than our peers. This information is shared with those seeking a foundation for seeking additional and making a decision based on all available facts. We should point out, that if you have any doubts that (a) we are a commercial enterprise and we make our living by selling and servicing communications systems, (b) we make no apologies for these efforts, and (c) we ARE opinionated! Hope that sets the record straight less our comments might be misinterpreted by those who may not agree with our comments.
We hope this information has been useful and to the best of our knowledge, it is correct at the time of publication. For additional information, we encourage you to do your own research and not take verbal or written representations by anyone (including us) as being factual. Check it out for yourself. We've given you our opinion and we encourage you to develop your own conclusions through additional research.
*Digital narrow band or very narrow band base stations generally provide equal if not better range than 25 kHz stations.