May Luncheon Review

 

Jim Dalke – Luncheon Presenter

Chairman Arthur Willetts started the meeting by providing reminders of SBE Webinars, RF Safety Course, & SBE University courses.  The Chairman brought awareness that the

Chapter Engineer of the Year Award nomination was extended to 6/13.  Also made awareness was that the Chapter is in the final month of the SBE Membership Drive and asked for present attendees to seek potential new Members.  The Chairman spoke about the possibility of a Chapter June tour, and also made mention of the July picnic while requesting that non-present Members be made aware of this big event.

Treasurer Jon Kasprick was asked to give a report about the state of the Chapter’s finances.  At this time, the Chairman requested candidates for the upcoming election by stating that all Members should consider service on the Board as a fulfillment of Membership potential, while making note that all seats are up for renewal.

At this time, Waveguide Editor Jim Dalke mentions that Bylaws have been updated on the Chapter website, and that the Bylaws are a good place to find the job description of each Board seat.  And on the subject of jobs, Jim includes that the jobs section of the Waveguide has also been updated.

The Chairman speaks for the Secretary and gives a proxy report that declares June 6th is the deadline for next certification testing application for the August testing period.  The Chairman relayed that the Chapter Awards nominations deadline is June 13th.  After this, the Chapter 16 Scholarship Committee formation was announced and future information would become available.  In consideration for the changing HAZMAT standards certification deadline which will occur June 1st, the Chairman asks that everyone refer to page12 of the February SBE Newsletter, The Signal, to mention to their supervisors and management about a possible need to be certified.  Next up,

NAB visitor reports were given by Dave Ratener & Jim Dalke.  Dave’s report mentions that HD Radio was being promoted and tabletop models were being touted, with prices now coming down to around $99.  He also said that attendance was around 90-100 thousand and there was a lot of international focus.  In Jim’s report he spoke of Clay’s speaking participation on the EAS panels.

Along the same lines, mention is made of new state of WA EAS handbook that is coming soon as discussed at the SECC meeting held in Ellensburg the day before.  Jim also said that he was asked to give a brief presentation on his 500kH booster project, in between Ennes Workshops.  He also added that Tuesday night in Vegas was SBE 50th Membership meeting with what seemed to be about 300 members.  Jim took a few photos of this meeting to the Chapter Members at the lunch meeting.  Additionally, Jim also attended HAM radio reception on Wednesday night.

After completion of the Chairman’s dialogue, the luncheon attendees were introduce to presenter, who happened to be the Chapter’s very own Jim Dalke who repeated his NAB presentation on “Coherent Single Frequency Networks for optimizing FM coverage” – or in other words, getting several transmitters sync’ed to reduce interference in an overlapping area.  Jim began by saying that this was his 97.7 FM booster project in which he has been working on for the last several years.  Jim displayed visual descriptions of several definitions of multi-transmitter installations.  He made note that a traditional booster by FCC definition is a signal used within the 60db coverage area of the range of the main transmitter.  This point is the criteria for licensing.  (Marty adds that this application is mostly for non-commercial and education stations, as a primary station cannot own a translator outside of its market designation.)

The original def of SFN was in an application stringing several transmitters together along interstate corridors.  Jim said that analog FM is focus of this project, not HD radio- as support is still growing. The concept of booster transmitter is to fill in shadow areas.  However, there are problems.  It would seem that just picking up the primary and boosting it would be simple but a receiver would have to be isolated from the primary so the receiver would know which signal to lock onto and avoid overlap interference, because the signal levels are close together and almost identical to multipath.

In his tests in his application, he made sure that the carrier frequency was as precisely locked as much as possible.  Then, the modulation envelope has to be precise as possible, which is hard because of small variations make this an almost impossible task by getting the deviation exact, and if it is not exact it will create more problems.  Next, and quite significant is propagation delay in the interference zone where the signals are approximately the same.

For frequency tolerance, the FCC tolerance is + or minus 2000 cycles.  GPS oscillators make this an easier process.  Doppler effect is also a consideration with a maximum 18 Hz shift involving multi-path.  Modulation characteristics all need to be precise.  From this introduction, Jim goes on to describe the project of taking the 97.7 FM from SouthMountain and using the booster in Auburn to fill in the Southcenter shadow.

By Arthur Willetts, Chapter Chairman