Digital Radio Coverage and Interference Analysis Project
Frequently Asked Questions
The following questions were received the week of May 8th, 2006. The answers to these questions are interspersed. Note that the due date for RFP's has been extended to May 31, 2006.
Does the 10-page limit for the narrative apply to one complete proposal or to each part of the two-part project – coverage and interference?
The complete proposal.
Is there a limit to the number of pages in supplemental materials?
No, Supplemental material must relate directly to the specific work scope in the RFP.
In the selected markets, does the proposal seek interference results to public stations with all stations in the market operating HD Radio?
The study seeks to define interference caused to existing analog and HD stations on an individual basis, within the selected markets. The study further requests an extrapolation of these results to all public radio markets at a time when all NCE stations transmit HD.
Are you seeking interference results for just 1st adjacent channels or both 1st and 2nd adjacent?
Yes.
Has the loss of service reported to CPB been to fixed receivers, mobile receivers or both?
Both.
Regarding translators, (a) are you asking for the impact of interference to main (primary station) signal reception by analog translators only and (b) are you also asking for results of interference to signals retransmitted by translators?
Yes.
Re: Part 1, Coverage, part B: HD Receiver Lab studies - In order to determine the effect of IBOC reception on current FM receivers, it appears that the RFP does not request test and verification of current analog receiver published specifications for Stereo 50 db quieting and usable sensitivity. Does CPB wish to have these factors considered?
Good engineering practice would require knowledge of analog receivers that receive interference from HD stations, so that the interference can be quantified and categorized by receiver type.
Under Part II, "Considerations for Stations," bullet #2: Are you implying that a digital signal may be available for reception where the analog has become degraded? It would seem that the question should be would analog fringe reception be improved by more sensitive receivers – or does your use of HD coverage here refer to the analog component of the hybrid HD signal?
There is no Part I "Consideration for Stations". There is "Consideration for Solutions" however bullet #2 does not seem to refer to the question asked, so we are unable to answer this question because of its lack of clarity.
The coverage study specifies "individual public radio station coverage analysis." Does that information need to be newly obtained for this study, or is it acceptable to compile data that already exist (as part of FCC filings, for instance)?
The information about individual station HD coverage would be obtained through the study. The FCC FM database lists all the operating parameters of the existing NCE stations and it would be used to project the areas of coverage and interference that need to be studied under this project.
Is it permissible to subcontract field work and/or lab tests to engineers or firms in the various localities specified for the study, rather than having the field work and/or tests all performed by the personnel contracted by CPB for this project?
Yes, if the sub contractor is qualified and when approved by CPB.
Concerning the "technical solutions" to extend the HD range to equal analog coverage, are those limited to solutions that are consistent with current rules and regulations and technical standards? Or is it acceptable to propose solutions that would require FCC action, such as (hypothetically) increasing authorized ERP to achieve 66 dBu? (That example is purely for purposes of illustration.)
Recommended improvements can be those that fit within current FCC rules and those that could be made with certain "practical" rules changes.
Ibiquity requires a license agreement with all companies that desire to purchase an exciter or other transmission equipment. Will CPB provide to the contractor a license from Ibquity to allow the contractor to purchase HD Radio exciters and other required equipment for the Lab and Field testing?
No.
Will CPB provide or is the contractor to provide the HD Radio receivers to be evaluated under the project?
CPB will not provide an HD receiver.
Is evaluation of the service losses for both analog and digital to be determined as "area", "population" or specific population groups broken down by demographics? Or - all three?
The RFP asks the vendor to identify commonalities in disenfranchised listeners… this may be areas, or ethnic demographics or both. Population affected would always be important.
Is there a specific time line for the project deliverables? The RFP mentions a one-year time frame for the entire project. Is there a specific CPB deadline when the entire project should be completed?
The timetable will be set by the vendor with approval by CPB.
On page 2, Part 1, it is specified to study at least 50 of the largest public radio markets and 25 smaller markets. Will CPB select the specific markets?
The markets are to be identified by the vendor after analysis as defined in the RFP and approved by CPB. A list of the markets will be provided.
I have responded to similar government bids and they typically are awarded to the lowest bidder, unless there is extenuating circumstances. Can you also confirm this?
CPB is definitely interested in finding the best price. Full detail on the criteria CPB will use in awarding the bid is found on the CPB web site under the banner of this RFP.
What is a "public radio station" in this context? CPB-funded only? Any non-com station? If the former (for example), how do we identify the CPB-funded stations? (Although few of these are in the non-reserved band, i.e. 92.1 MHz and above, others will also be adjacent to the non-reserved band.)
CPB-qualified stations are those receiving funding under CPB's Community Grant service program.
How do we identify 50 of the largest public radio markets?
Part 1 says Study at least 50 of the largest public radio markets in the U.S. and 25 smaller markets where significant service is provided by public radio stations located outside or at the periphery of the market.
The markets to be identified will have at least one public radio service that provides service to the market where the 60 dBu of the station does not cover the entire market.
The top 50 public radio markets in 2003.
Are the 50 large markets supposed to have peripheral coverage, or does that apply only to the 25 smaller markets?
All markets identified should have at least one station that provides such coverage.
Q: How small is a smaller market? Do they want rated markets or unrated markets (rural areas served by stations from adjacent larger markets)?
For the purpose of this RFP, smaller markets are identified as being outside the top 100 markets.
Is Part 1 of the study to be conducted without consideration of interference sources? Just the service differential of 50 dBu LR (or other similar methods) and 66 dBu LR inside the 50 dBu contour?
Part 1 and the follow up after measurements of Part 2 are to be carried by identifying the "interference free" coverage areas within the 50-66 dBu LR of the identified stations and markets.
Does that 66 dBu service level pertain equally to rural areas? The listed Tomorrow Radio study markets were Wash DC, NYC, SF, and LA.
CPB does not have this information, however for the purposes of this study the 50 – 66 dBu signal contour levels can be maintained for rural as well as urban areas.
Translator interference analysis: includes study of input frequencies. For the translator sample, we would need to acquire data on the input methods (direct off-air from the parent station, via another translator, satellite, microwave, etc.).
Some translators go to extreme means to get the input signal off-air, using high-gain directional antennas. Input data is not necessarily in the FCC records.
Translators on 1st adjacent channels with off-air feeds, probably not a lot of those. But will those on 2nd adjacent channels have input problems from the parent station?
Answer to question posed is one of the answers CPB seeks in this RFP.
Assumptions about receive antennas for LR type studies. Assume omni, no gain, 2 meter AGL?
Assume omni, no gain, 2 meter antenna height.
Is it acceptable to assume 100% power at all vertical angles? Or do we need to chase down vertical patterns? We can't possibly do that for all interference sources, but maybe we can do it for the public radio stations being studied.
Since the interest in these studies is coverage and interference at the periphery, beam tilt should be considered. Considering power at all vertical angles is not required.
Could we include any land use or local clutter losses?
No, correction for land attenuation should be made through the information gained by actual measurements. (See Part 1, C)
Part 2 asks "How does the level of anticipated HD interference in the non-commercial FM band differ from that expected in the commercial FM band (where the allocation system differs)?" Are they asking for a comparison of public radio stations in the non-commercial and commercial bands? Or would we also need to conduct some studies of commercial stations?
A comparison of public radio stations operating in the commercial FM band is not requested. An analysis of the extent of non-commercial band HD interference compared to the HD interference within the commercial band is. Basically, CPB is interested in the impact of HD interference caused by the NCE contour-to-contour allocation system, used for the majority of public radio stations, as opposed to the primarily minimum-spacings based commercial allocation system.
In Part 2, are we studying impact on both the analog and IBOC service of the public radio stations?
Yes.
Should we include FM translators as interference sources? (analog only?)
Yes.
Should we include TV6 (TV, DTV, LPTV, translators) as interference sources?
This is left as an activity to be proposed by the bidder if the bidder has, or develops knowledge in the course of the project, that the exclusion of such stations could make the results inaccurate.
There is likelihood that the laboratory interference studies will show different D/U ratios at different levels of desired signal strength. Will we need to build a variable D/U ratio into the interference studies?
Yes, if it is required to maintain the accuracy of the study.
And do we just use the FCC D/U ratios for the baseline study?
The standard FCC U/D can be used initially to determine the interference free analog coverage. The receiver measurements are to be used to adjust FCC's U/D (if necessary) for the final interference calculations detailed in Part 2 of the study.
What does footnote 1 mean? Are they expecting us to (for example) apply the July 2004 population estimates to the Census 2000 block centroid data?
Yes.
The 2004 estimates are on a county-by-county basis, so one would have to breakout the block centroid popcounts by county and then multiply by the county's change in population.
Agreed.
Would the option be an add-on to the main project? It would be based in large part upon the main study, so shouldn't be a separate project.
The option is to be quoted as an add-on to the existing study, simply expanding on the number of stations for which a coverage/interference report is generated.
And just how many CPB-qualified public radio stations are there? It's hard to provide a cost to prepare these studies without that number.
What about impact on SCA reading services for the blind: should it be studied, and also, should impact on LPFM's be a part of the study?
This additional work is not a part of the requested RFP.
Because listeners to specialized formats (if public radio can so be described) often are willing to use better receiving systems (receiver and antenna) and may have higher in-home or in-office percentages. How much attention should the study pay to the relative characteristics of receivers?
This question is based on an untested assumption. Public radio listeners should be treated as having the same antenna systems as other listeners.
Our understanding is that the performance of the available HD radios is pretty lackluster. Whether this is poor receiver design or the basic systems problems is unknown. Maybe a "reference" quality receiver should be included in the testing. Should we assume that this is a part of the effort?
The reference receiver should be included if it would represent the best available characteristics of a future consumer receiver.
It would be advisable to limit field work to confirming the models. VHF field measurements always seem like the most amount of work for the least accurate results, as the recent NPR efforts confirm. Please comment.
The field work should establish the accuracy of the developed prediction model and coupled with the laboratory measurements establish a factual basis for predicting HD to analog and HD interference.
Analog U/D protocols are a mess. ITU-R has failed to maintain its Recommendations. They are for monaural signals with average modulation of about 30%. For about the past 35 years or so, everyone doing U/D studies has invented their own interfering signal and measurement method. The one we have a reasonable comfort level with is the tone method developed by the late Eric Layton for the Quadraphonic testing in the mid 70's. We need to know if CPB is comfortable with letting the contractor develop/select a method.
CPB does not believe that any existing models are adequate for this project and therefore one aspect of the work scope is to define and test a model that based on measurements in the field and in the laboratory can be used to predict interference levels on a wide basis.
It is important that this study be conducted in an environment that is isolated from third party interests. Is CPB prepared to resist efforts by others to modify protocols and/or eliminate "unfavorable" test results and conclusions there from?
CPB requests that bidders define any real or potential third-party conflict of interests.