Webinar Q&A: Uplink Testing Requirements

November 14, 2024

This Q&A is a supplement to our “Requirements for Uplink Testing with Public Safety In-Building Enhancement Systems” webinar from November 14, 2024. All questions are from actual webinar participants, but some questions have been edited for clarity, and similar questions have been combined.

If you need a refresher, you can view replays of our webinars and other videos here. If you have any further questions, or would like to schedule a training or demonstration, please contact us.

Q) Will you visit my area to provide training?
David Adams: Contact us. We might already be planning something in your area. We actually have SeeHawk® Monitor and Central in use in Central NC (High Point / Greensboro / Winston Salem), which was mentioned in the webinar, so we are likely to be returning to that area.

Q) How can I watch past webinars?
David Adams: You can view previous webinars under videos in the Resources section of PCTEL’s website.

Q) What resources do you have for beginners in ERRCS / BDAs? Do you offer refresher training for those who have already been certified?
David Adams: Our public safety tester certification training is a great beginner course, and we offer re-certification training as well (required every 2 years). Additionally, the training videos and user guides are always available for review on the certification training site for those who keep their certification up to date. You might also find some of our publicly-available videos  and other customer support resources helpful.

We are also considering offering additional training events in the future.

Q) Do you have a tool that addresses uplink issues? Should I learn more about SeeHawk® Monitor? Do you have a webinar available that goes into more depth about uplink testing with SeeHawk Monitor?
David Adams: Yes! SeeHawk® Monitor is our system that enables automated uplink testing, and has many other features that are useful for operators of critical communications networks. We covered SeeHawk Monitor in more detail in our previous webinar on uplink testing, from September 2023. We can also provide you with a presentation if you contact us.

Q) When does FBER come into play?
David Adams: Frame BER (FBER) is for in-service channels carrying normal traffic. FBER is calculated on Frame Bits.

Q) One of your examples of marginal signal quality showed good FBER. Why do you say it is marginal?
David Adams: In this case, the FBER shown was a single instantaneous measurement, making the SINR a much more reliable indication of signal quality. Bit errors are bursty, not static, so a BER or FBER value should be averaged over a period of time that depends on the data rate.

Q) When should BDA signal dominance be required? i.e., where should the handoff between the Macro signal and BDA be made?
David Adams: The BDA should be dominant everywhere inside that it is intended to cover (i.e. not on floors where there is no DAS and the outside signal is intended to be used). The network signal should be dominant outside of the building.

Q) How about multi-floor BDA dominance?
David Adams: It is difficult to measure the same signal from antennas on different floors. However, a good SINR value would indicate no significant interference between the floors.

Q) I’m trying to get AHJs to use signal quality (SINR & BER) as DAQ equivalency if they can’t provide radios for DAQ uplink and downlink testing. Do you have any advice?
David Adams: Refer them to the SBC website, which has lots of useful information, as well as the TIA TSB 88.3G documents. You should also encourage them to go to a local SBC seminar event (which are free for AHJs and other public safety officials to attend).

Q) Is there any place to find better info as far as determining the correct frequencies to amplify? We are Radio Reference dependent and not always confident. Any help appreciated.
David Adams: Always find a way to get a government employee to give you this information. It’s the only way to be sure.

Q) How would I test UL for a non-trunked system that does not have an active control channel?
David Adams: Our product can test UL on traffic channels. The tester must carry a test radio that is authorized on the network and locked to a test channel.

Q) At a recent SBC Seminar, Alan Perdue said that you should be using DAQ testing instead of dBm. Is that correct?
David Adams: Alan meant that you should measure quality instead of power (RSSI in dBm). DAQ can be assessed more accurately by measuring SINR than through a voice test.

Q) Can we check TETRA systems also?
David Adams: PCTEL equipment can measure TETRA DL SINR and power, but only power on the UL as of today.

Q) Can we use SeeHawk® Monitor to connect to the core network and monitor several uplink from different sites at the same time?

David Adams: SeeHawk® Monitor works by measuring the RF signal entering the radio site. Our SeeHawk Monitor Platform Manager software enables you to remotely monitor signal at multiple radio sites simultaneously by connecting to multiple SeeHawk Monitor RTUs (Remote Test Units) located at different radio sites. However, SeeHawk Monitor does not connect to the core network.

Q) How can you truly test uplink if the license holder/AHJ won’t give you a frequency or handheld radios to test with?
David Adams: Testing uplink requires the involvement of the radio system.

Q) Have you seen better isolation in buildings with E glass windows?
David Adams: Yes, absolutely.

Q) Do you see RF Interference from multiple donor antennas where one is much closer to the site than the other?
David Adams: Yes, absolutely.

Q) What is the difference between SINR and C/I or CINR?
David Adams: C is Carrier (the central frequency). S is the modulated signal. These quantities are very similar. They are generally used interchangeably for the purposes of understanding signal quality.

Q) I have used Motorola Voyager to test uplink in the past. Obviously we needed to have the equipment at the site. I am presuming then that we need two PCTEL devices, one at the site and one at the location under test. Correct?
David Adams: You would use a PCTEL public safety testing kit with an IBflex® scanning receiver and SeeHawk® Touch software at the location under test. At the site, we recommend using SeeHawk® Monitor, but it is also possible to configure a second public safety testing kit to measure uplink at the site on a temporary basis.

Q) We ALWAYS calculate the FSPL and target to hit the site at -79dBm.
David Adams: That is considered a good value, but the radio system may provide different values.

Q) Is there an acceptable SINR # to use as a reference? Is 20db an acceptable #?
David Adams: See the table in the presentation. We highly recommend adding some margin to those values. Usually 20-22. (The presentation was made available to those who registered for the webinar. Others can contact us to request a copy.)

Q) Should we be checking donor antenna VSWR?
David Adams: Yes.

Q) Can you say anything about the usefulness of taking snapshots of conditions vs longer term monitoring?
David Adams: All project tests are snapshots by definition. Best practice is always to supplement these with different forms of continuous monitoring.

Q) How can we help convince the radio shop to install the monitor device on their end?
David Adams: We can join you on discussions, presentations, and even trials. Please contact us. We also have some brief SeeHawk® Monitor Use Cases from early adopters on our website, and we are developing more in-depth case studies.

Q) Can you send a link to the TIA TSB 88.1E chart that compares the DAQ to SINR?
David Adams: TIA sells their documents and what we have is restricted. TIA TSB 88.3G is actually the most current version. We also offer a free download of our Public Safety Radio Networks poster, which includes some information based on TIA TSB 88.1E.

Q) Is it problematic to add multiple BDAs in an area with P25 Phase 2? Is there a limit to the number that should not be exceeded?
David Adams: Potential problems and situations that cause these problems are numerous. That is why tests are required, and some jurisdictions might have outright restrictions. The presentation did cover a test for “Cross Building Isolation.” There are ways to address most problems.

Q) You mentioned inter-symbol-interference (time delay). It’s a factor of both time and signal level. Can you tell us more (min delay, min signal deltas)?
David Adams: The best place to look for this information is TIA TSB 88.3G. It includes relevant charts, such as power vs. delay.

Q) At what percentage of completion of a new building should you do an initial site survey?
David Adams: The initial test can be done any time, but you get the best guidance once windows are in. But the final survey should always be done when the building is complete and in use.

Q) We are having problems affiliating our portables with our BDA. What’s the best approach to troubleshoot?
David Adams: Radios affiliate with the network through the BDA. Be sure your radios were configured for access by the network. Then you need to examine the Uplink signal over the entire path (into the BDA, leaving the building, arriving at the site, etc.).

Q) How can I look up more information on how to set up multiple floors on PCTEL test equipment?
David Adams: Contact our support team (select the Test & Measurement tab at the top of the form).