Reflections at Lake Poona, Great Sandy National Pk & Rainbow Beach

Lake Poona bush walking (sans 4WD)

Lake Poona is accessible from Freshwater Road just west of Rainbow Beach. The lake comprises part of the Great Sandy National Park (NP). The park comprises some 220,000 hectares according to Bonzle and is tentatively World Heritage listed. The colourful Great Sandy NP (below) is sandwiched between Fraser Island & Tewantin – Noosa.

4WD vehicle driving south of Rainbow Beach © 2014 FM DXing

4WD vehicle driving south of Rainbow Beach © 2014 FM DXing

The Lake Poona walking track starts at the Bymien picnic area (map). This area is accessible via a loosely graded dirt road which is officially deemed suitable for 2WD vehicles.

To access the lake, a challenging walk (4.2 km / 2.6 mi return) is required. There is no direct vehicular access to Lake Poona. With a couple of short breaks, the walk took 43 minutes for its first half. Based on alitmeter readings, the elevation rises from 183 m (600 ft) to well over 240 m (787 ft) through the mid-point of the walk. Because of small rocks that are loose underfoot on the track, undertaking the walk is particularly challenging in the dark, even by torch light! It is therefore recommended to leave the lake and commence the return half of the walk at least half an hour prior to sunset.

Who is this tool at Lake Poona? © 2014 FM DXing

Who is this tool at Lake Poona? © 2014 FM DXing

The colour of the water in Poona Lake (above) is distinctive. It forms as a result of tea tree leaves that fall into the water. The pristine lake tastes good; the home brewed ale afterwards in the apartment… even better! This blogger roughly estimates that the lake is at least 226 m (741 ft) wide and 574 m (1,883 ft) long…  assuming seasonal rainfall maintains its capacity! The expansive lake can be easily seen from an aircraft. Fishing enthusiasts should be aware that reports suggest that fishing in Poona Lake is unlikely to be a fruitful endeavour!

4WD driving permitted on Rainbow Beach © 2014 FM DXing

4WD driving permitted on Rainbow Beach © 2014 FM DXing

The walk, which culminates at the south east corner of the lake, seems to be surprisingly unpopular. Even on a busy summer Sunday, with the Rainbow Beach patrolled surf beach ‘pumping’ nearby (above), only two thirty-something walkers were seen during the course of the walk.

Expansive Lake Poona © 2014 FM DXing

Expansive Lake Poona © 2014 FM DXing

Despite the obvious potential (above), there was no swimming undertaken on this occasion due to lack of time. The time of arrival was 5:30 pm. About three minutes were spent on a brief survey of FM radio reception. This act of madness was done discreetly, when nobody else was around.

Only very rudimentary portable radio equipment (below) was able to be taken on the bushwalks. Frozen water bottles, insect repellent, a ‘smart’ phone (apparently?), torches & two video cameras take precedence!

Tree hugging radio at Lake Poona © 2014 FM DXing

Tree hugging radio at Lake Poona © 2014 FM DXing

At the lake, signals from Bundaberg (93.9 MHz, N), the Darling Downs (100.7 MHz, SW) & the Gold Coast (89.3 MHz, S) at a distance of 224 km (139 mi) were clearly audible on the Tecsun PL-300WT (below). The 80 kW FM western ‘beasts’ broadcasting from Biggenden (116 km / 72 mi) were so strong the signals were bleeding onto adjacent channels such as 99.5 MHz. Jet-scattered transient signals from Coffs Harbour were NOT receivable at the lake. Tropospheric Index: light blue.

The highest point of the walk is roughly about one kilometre from the lake. At this point is a grassy clearing of about 25 square metres (269 square ft) with a basic selection of log ‘seating’ to recharge one’s depleted physical ‘batteries’. Unfortunately, the towering trees nearby attenuated FM signals at this area. This seemed to negate the benefit of the higher altitude, as signals listed above that were clear at the lake were noticeably absent.

Tecsun PL-300WT radio at Lake Poona © 2014 FM DXing

Tecsun PL-300WT radio at Lake Poona © 2014 FM DXing

Great Sandy NP radio observations

In contrast to Lake Poona, at two locations a short drive away, Coffs Harbour’s RN on 99.5 MHz would ‘boom in’ via jet reflection at this time of day. These were accompanied by daily late afternoon showers which were likely indicative of flat atmospheric conditions. These two trips are detailed below:

A third of the way (3 km / 1.9 mi) to Neeb’s Waterhole (map), the tour was forced to stop on a hill (where the road parts in two directions) that is roughly estimated to be 50 m (164 ft) ASL using Google Earth. Access to the waterhole was previously possible via Mullin’s carpark through Cooloola Way with a 4WD vehicle (that is, four-wheel drive or SUV, sport utility vehicle) but is now closed for repair to all traffic due to severe flood damage, which necessitated turning the vehicle back.

On this hill in Cooloola Way, the extensive 4WD metal body (below) was used as a highly effective ground plane. The radio was placed on the high roof of the vehicle. The Tecsun radio battery ground was connected to the roof and the telescopic antenna fully extended vertically. The base of the telescopic antenna is NOT touching the metal roof, only the ground wire does.

4WD beach route between Middle Rocks & Double Island Pt © 2014 FM DXing

4WD beach route between Middle Rocks & Double Island Pt © 2014 FM DXing

This yielded far better results than the 4WD factory radio. As seems to be commonplace, the Toyota’s telescopic antenna was too short. The FM telescopic wasn’t captured on film, but is probably only two-thirds of the length of the portable receiver’s telescopic antenna. Worse, the factory receiver did not feature sufficient selectivity for the modern congested FM band.

Although worthwhile for long distance FM reception, this ‘portable on the roof’ approach unfortunately yielded this crazed enthusiast dozens of insect bites that affected ‘sleep quality’ for the remainder of the vacation!

The highlights were Stanthorpe (103.3 MHz, SW) & Coffs Harbour (99.5 MHz, S) at distances of 302 km & 476 km (286 mi) respectively. A ‘rebelliously-strong’ signal from Beaudesert (90.5 MHz, S) was a pleasant surprise at 210 km (130 mi). It’s hard to maintain interest when insects are feasting on the back of one’s knees, but signals towards the north & west seemed lacklustre with nothing obvious further than moderate strength Bundaberg, 146 km (91 mi)! Tropospheric Index: unknown.

At the Tin Can Bay Volunteer Coast Guard (map), a simpler arrangement was used since a conventional vehicle was able to be used. Obviously this is more convenient (translation: ‘bite free’ comfort) & yields superior results to a portable receiver sited in the ‘middle of nowhere’, although perhaps it does not offer as much ‘quirky’ enjoyment. Again, a Blaupunkt ‘Sharx’-enabled radio with an amplified Shark Fin (an appropriate match for pun enthusiasts?) was effective, as is regularly used.

Overlooking Tin Can Inlet west of Rainbow Beach © 2014 FM DXing

Overlooking Tin Can Inlet west of Rainbow Beach © 2014 FM DXing

The car was driven to a parking space overlooking Snapper Creek near the Coast Guard’s antenna arrays (above). At this spot, Bundaberg (93.9 MHz, N) & Brisbane (104.5 MHz, S) were strong. Satisfactory reception was possible from Redland Bay (100.3 MHz, S), Ipswich (94.9 MHz, S), the southern Gold Coast (95.7 MHz, S), Beaudesert (89.7 MHz, S), Cherbourg (94.1 MHz, W) & Coffs Harbour (99.5 MHz, S) at a distance of 491 km (305 mi). North-western signals from Gladstone (93.5 MHz) & Rocky (103.1 MHz) at respective distances of 287 km & 348 km (216 mi) were weak. Tropospheric Index: dark blue.

Great & Sandy but dense terrain

The Great Sandy NP comprises many ranges of dense rainforest. Not only does this result in exhausting 4WD driving for relatively inexperienced drivers (like this long-suffering writer) but these terrain characteristics also pose a significant obstruction for long distance FM reception towards the south at Rainbow Beach.

Leisha track entrance to beach © 2014 FM DXing

Leisha track entrance to beach © 2014 FM DXing

Conversely, it is highly likely that this is also the reason for the FM reception deficiencies at Noosa towards the north, discussed in previous posts. Tewantin – Noosa is located near the southern boundary of the park. One afternoon, when checking briefly on the 4WD on the beach near the Freshwater camping & day use area (below) a haul of southern stations were found. These included the Gold Coast and were easily detected in flat conditions. Freshwater’s facility is NE of Teewah Beach, accessible by 4WD.

Freshwater track entrance to beach © 2014 FM DXing

Freshwater track entrance to beach © 2014 FM DXing

Much like Noosa, reception to the north west is obstructed by mountains. Fishing, surfing, swimming, walking, backyard cricket or drinking is probably a more fulfilling way for prospective campers to pass the time in this part of the park (below) than playing with a portable FM receiver!

Driving north towards Rainbow Beach © 2014 FM DXing

Driving north towards Rainbow Beach © 2014 FM DXing

Located NE of Freshwater camping & day use area is Double Island Point Conservation Park. Atop a cliff is the popular lighthouse attraction, accessible via walking track (below). The Double Island Point lighthouse has operated since 1884. The ‘light’ which guards passing ships from the rocky headland is supplied via solar electric panels. The lighthouse is an official weather station, often featured on television.

Lighthouse cliff track, Double Island Pt © 2014 FM DXing

Lighthouse cliff track, Double Island Pt © 2014 FM DXing

Rainbow Beach accommodation (sans 4WD)

Rainbow Beach (below) has a ‘party-like’ tourist atmosphere. To this writer, this felt reminiscent of Airlie Beach, the gateway to the Whitsunday Islands without the oppressive tropical summers. Granted, there is not the variety of restaurants & nightlife the Airlie Beach destination offers. Both destinations share the same sub-tropical climatic classification.

Rainbow Beach © 2014 FM DXing

Rainbow Beach © 2014 FM DXing

Rainbow Beach seems particularly popular with Dutch, German, Polish & Swedish twenty-something tourists. During the week, the location (cue The Specials’ classic, please deejay) almost resembles a ‘Ghost Town’!

It’s probably unsurprising as there is barely one school and no major supermarkets in the locality, with the overwhelming emphasis on tourism. Nearby Tin Can Bay seems to be the business, residential & recreational fishing and hub of the region.

Rainbow Beach to the south east, including Double Island Pt © 2014 FM DXing

Rainbow Beach to the south east, including Double Island Pt © 2014 FM DXing

Rainbow Beach’s weekday ‘slumber’ (above) is perhaps ideal for exploiting Rainbow Beach’s wonderful potential for FM reception. It is remote! How remote? The only local broadcast is a one watt Christian FM narrowcaster; on MW it is Classic Hits 4GY. The region only requires 75 watt digital television translators.

Tropospheric Ducting: Pack a yagi or get high!

Even during instances of ‘fair’ tropospheric ducting in mid-March (Autumn), distant reception is awesome. These were indicated by a light blue colour on the Hepburn tropo forecasts, easily viewed via even the most rudimentary cellular phone. (Conditions were confirmed after the vacation ended using the Marine Tracking peaks on the graphs at Gladstone).

Long distance FM reception from the north west as far as Mackay (687 km / 427 mi) is possible at Rainbow Beach. Just as rewarding is hearing the numerous low-powered mine relays from the same azimuth, rebroadcasting commercial stations Zinc (aka 4CC), Sea FM, Rebel & Breeze.

In total, 92 FM stations were logged at Rainbow Beach over three evenings. These included two re-broadcasts of cable television sporting channels, typically servicing large caravan parks.

As mentioned above, the obstructive nature of the Great Sandy NP at Rainbow Beach enable FM broadcasts from Gladstone (292 km / 181 mi) to obliterate those on the Sunshine Coast (100 km / 62 mi). This is a very pleasing terrain side effect, since the Gladstone broadcasts emanate from a low-elevation site with a tenth of the power of the coast stations!

Access to a collapsible three or five element FM yagi (from $45) is recommended for receiving pleasant ‘quieting’ signals from the north west (such as Mackay) in Rainbow Beach. Not all accommodation may be ideally suited for the placement of a ‘stealth antenna’. Huh? Essentially, a stealth antenna in this context refers to the erection of a tripod-mounted small yagi on the balcony during darkness between 7 pm – midnight. A folded dipole resting on a balcony’s glass or wooden table may suffice. (The dipole is easily detached from a surplus five or eight element FM yagi).

Carlo Sandblow to the south, including Double Island Pt © 2014 FM DXing

Carlo Sandblow to the south, including Double Island Pt © 2014 FM DXing

Rainbow Beach’s elevated region is characterized by a gradual rise from beach level (i.e. the Pacific Ocean) to 87 m (285 ft) near the Cooloola Drive reservoirs. These water towers adjoin the extremely popular Carlo Sand Blow lookout (108 m / 354 ft ASL), so these are easy to spot! The Sand Blow is pictured above & below.

Unless one is lucky enough to secure scarce accommodation located around here (the author did not), experimentation with a portable receiver’s telescoping monopole antenna is virtually guaranteed to be frustrating as the effects of a federal budget! Unlike many holiday locations, at Rainbow Beach there are simply no towering high rise apartments on offer. Typically towers partially offset the performance of a ‘lossy’ telescoping antenna.

Carlo Sandblow to the south, including Double Island Pt © 2014 FM DXing

Carlo Sandblow to the south, including Double Island Pt © 2014 FM DXing

Provided one pays attention to the hilltops and gets mobile, there are still plenty of other alternative methods to ‘get in on the action’. In fact, one evening the Mackay stations were even audible via tropo in the car, albeit only on the western crests of Rainbow Beach Road. Reception from this north western azimuth seems optimal when this road transitions into Tin Can Bay Road, approaching Wolvi near Gympie. Signals from Mackay were typically heard just above the noise floor.

Distance calculations computed using FM Scan, with base (apartment) reception undertaken with a Yamaha TX-930 component tuner.

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FM USB Tuner Shootout: PC Ear vs Instant Radio (ADS Tech RDX-155)

Welcome to another radio shootout, Boxing Kangaroo edition! These shootouts feature ‘dirt cheap’ radios and are intended to appeal to a variety of different potential audiences, including terrestrial FM radio listeners and hobbyists interested in elementary electronics or FM reception capabilities.

Boxing Kangaroos in the zoo © 2011 Scott Calleja

Digital Signal Processing on the cheap?

At the time of writing, the cheapest Chinese portable FM radio currently available incorporating Silicon Labs’ (Silabs) Digital Signal Processing (DSP) costs about $49 including delivery. This model is the Tecsun PL-606. For those with a laptop and access to a directional antenna, USB computer devices with the SI4700/01 integrated circuit (IC) are considerably more inexpensive, representing a cheap entry to Silabs DSP.

 Tecsun CR-1100 © 2013 James Case

 Tecsun PR-380 © 2013 James Case

The contenders: Two popular Silabs USB FM tuner

Instant FM Radio (Instant Radio) costs about $17 including delivery.

USB FM Radio Player © 2005 Silicon Laboratories

MP3car.com ADS Tech RDX-155 Instant Radio under Windows 7, Canberra Australia

Geeks.com ADS Tech RDX-155 Instant Radio marketing photographs

PC Ear FM Radio Player © 2014 FM DXing

PC Ear costs about $17 wholesale but is no longer readily available new.

PC Ear unboxed © 2014 FM DXing

Gunning for the best: PC Ear versus Instant Radio

A rudimentary inspection of the datasheets suggest the FM sensitivity measurements are equivalent for the Silabs ICs inside PC Ear and Instant Radio. To test this, a modest directional antenna was connected to the devices. Both devices were housed in a metal enclosure with two suppression chokes and operated with a Radio Frequency (RF) quiet laptop running from battery power.

Reception conditions were well below average with heavy, unrelenting rain. 15 stations were chosen for the test. Of these, 13 stations were detected with the minimum signal strength of 0, where signals are just audible above the noise floor. Because of the heavy rain, two of the usual weak signals were not audible during the test and accordingly, do not appear in the performance table.

Software

PC Ear does NOT support firmware upgrades using the Windows-based Silabs configuration software utility. Firmware updates to PC Ear can be done under Ubuntu/Linux, but the process may be complicated. The Silabs Radio DLL software appears to function, but audio issues were evident when tested briefly with PC Ear. According to the developers, it is supported.

The upgraded firmware was used with Instant Radio. The upgrade was performed per the ADS Configuration user guide instructions for Silabs Radio DLL, developed by Beezer, Guino and Pete.

Characteristic PC EAR  INSTANT RADIO
Tunable frequency range 76 – 90 MHz, 87.5 – 108 MHz 76 – 90 MHz, 87.5 – 108 MHz
Circuit board approximate size 1.3 x 0.6 inches 2.4 x 1.1 inches
Tuning steps 50 kHz 50 kHz
Radio Data System support No Yes
Software support USB Radio 2.0-3.0 (supplied), FM Signal Strength Analyzer 1.0.0.19, Silabs Radio DLL, Silabs configuration software utility. Instant Radio 1.0.0.11 (supplied), Silabs Radio DLL, FM Signal Strength Analyzer 1.0.0.19, Silabs configuration software utility.
Hardware version PC Ear 1.77 Silabs 1.7.15
Firmware upgradable No, Please refer to body of article Yes, ADS NoiseMod Primary.dec

The software support listed in the characteristics table (above) is NOT exhaustive. Please understand that the priority was to test reception performance.

Any frequency (or broadcast) can be easily recorded for hours ‘on schedule’ using third party Windows audio recording schedule software such as Fox Magic Audio Recorder (free) and High Criteria Total Recorder Professional ($36). The software supplied with the devices also offers recording ‘on demand’. ADS Tech Instant Radio software is especially recommended for this purpose, since it offers high resolution 96 kHz uncompressed recording capabilities.

Closeup of ADS Tech Instant FM Music PCB © 2014 FM DXing

Comparative performance

PC Ear is constructed on a double sided printed circuit board, whilst the Instant Radio device uses a much larger single sided board (above). Unsurprisingly, both designs feature surface mount components.

RADIO STATION FREQUENCY (MHz) PC EAR MAXIMUM SIGNAL STRENGTH (BARS) INSTANT RADIO MAXIMUM SIGNAL STRENGTH (NUMBER) INSTANT RADIO RDS DECODING DISTANCE (MILES)
90.5 0 3 No 43mi (200 W)
91.1 2 – Quieting Mono 19 – Quieting Mono Instant 35mi
92.1 0 6 N/A 43mi
93.7 0 0 N/A 62mi
94.9 0 6 No 27mi
95.3 1 6 N/A 88mi
98.5 1 – Quieting Mono 9 – Quieting Mono N/A 88mi
99.4 0 0 No 48mi (2 kW)
99.5 No signal, Slight high adjacent channel interference (99.7) 0 N/A 208mi
102.9 0 6 N/A 48mi
104.5 4 – Quieting Stereo 50 – Quieting Stereo Instant 11mi
105.7 0 5 No 48mi
107.7 5 – Quieting Stereo 57 – Quieting Stereo N/A 11mi

Instant Radio consistently offered a slight edge with superior adjacent channel suppression on one station and the advantage of RDS. PC Ear did ‘stutter’ occasionally on one RDS-enabled station. A change to the device settings (below) and immediately unplugging the device solved the problem. This trivial audio issue could not be replicated again after 15 minutes of listening to the station, nor the next day.

PC Ear FM Radio Player custom settings © 2014 FM DXing

There were no consistently observable differences in sensitivity, audio quality or immunity to internally-generated spurious noise (interference) between the devices. This result was somewhat unexpected because PC Ear is rumoured to be an earlier Silabs USB tuner prototype with its share of critics on the world wide web. Perhaps the critics use the supplied wire antenna (in both devices, 29 inches long) and therein lies the problem? But the test suggests PC Ear performs just as well as Instant Radio with a directional antenna. If anything, the test was biased against PC Ear because of expectations the device was of poor design quality relative to its sister models.

Performance improvements

It should be stressed that Instant Radio and other Silabs devices require antenna modifications (below) for connection to a directional antenna such as a rooftop television antenna. Soldering skills are recommended for permanence. The use of other alternatives to ‘mate’ the device with an external antenna, such as passive induction as used in some mobile broadband device antennas might also be feasible, but discussion is beyond the scope of this shootout.

With the additional expense of a metal enclosure, shielded five metre USB cable, pre amplifier and several ferrite suppressors, the total cost equates to approximately $135. Many readers may already own much of this equipment, but it does represent a potential outlay. In this blogger’s opinion it is only worth pursuing such a project for the sheer fun of experimentation!

Instant Radio customization © 2014 FM DXing

Notwithstanding the extra Do It Yourself (DIY) effort and cost required to extract the device’s DX potential, Silabs tuners feature satisfactory signal separation and strong signal handling. With the above modifications, Instant Radio is sensitive enough for daily signals from in excess of 265 miles. Momentary meteor pings from distant FM stations are possible to receive. Although untested at the time of writing, it is anticipated that modifications to PC Ear would accomplish the same. The bottom line is that these Silabs devices were designed for learning projects. It is NOT suggested to ‘throw good money after bad’.

Comparative performance with expensive stand alone tuners

As one should realistically expect because of the tiny footprint and price, the devices are outclassed by stand alone tuners with a proper shielded tuner module. Even with a preamplifier used in-line to desperately boost sensitivity, this is apparent. Head-to-head, the following tuners or SDRs (tested without preamplifiers, using the same antenna) all noticeably outperform Instant Radio (FM usable sensitivity* is listed in brackets):

  • Blaupunkt Casablanca CD51 (1.68 microvolts),
  • Elad FDM-S2,
  • Sherwood TX-5090 RDS (1.58 microvolts),
  • Yamaha TX-950 (0.8 microvolts).

For example, in a ‘dead-of-winter’ test, the Blaupunkt automotive receiver consistently achieved better performance than Instant Radio. Improved RDS sensitivity meant that the car radio decoded digital RDS data from two extra stations. Like all models in the Sharx range, the car radio more readily discriminated stations spaced 100 kHz apart.

Instant Radio was capable of receiving 2/3 of the 15 weak signals chosen for the test, whilst the car radio nabbed 93% of weak signals! The Silabs devices enable reception of the same stations from in excess of 265 miles as standalone tuners. However, this reception will obviously be more transient and weaker signals are unlikely to be audible. From a DX enthusiast’s perspective, that may be a frustrating prospect.

The number of RDS decodes achieved with Instant Radio was equivalent to the Bauhn ADS-215 dual band portable radio connected to a carefully aligned rabbit ears antenna mounted near a window. Invariably, Instant Radio outperformed the Bauhn portable radio using its inbuilt telescopic antenna.

DealeXtreme.com PC Ear marketing photographs

Summary

The device incorporating the Silicon Labs’ SI4701 IC (marketed as ‘Instant Radio’, above) is one breed of flash-drive sized computer tuner that offers modest potential for weak FM signals. It suits receiving locations with a congested FM band. Its full RDS capabilities can be exploited in locations where broadcasters support the system. PC Ear also offers similar performance, without RDS decoding.

All software tested works successfully on both receivers without noticeable bugs. There is a range of tuning software to choose from. Both Silabs devices are suited to DIY modifications.  Users of Instant Radio benefit from access to the latest firmware.

Further reading

Gadget tunes in to FM via USB

Instant Radio for distant FM reception

Instant Radio satirical shootout

Instant Radio slideshow

Radio recording saved the radio star

Silabs Radio DLL

* Standard DIN sensitivity specifications, tested with THD 3% & S/N of 26 dB. Official data, sourced from manufacturers. Lower numbers (approaching zero) indicate the best FM sensitivity. The Elad FDM-S2 sensitivity is measured differently from conventional tuners. This SDR offers better than 2 microvolts using the 12dB SINAD measurement on the extended FM band.

As always, the writer has no affiliation with any retail merchant or product manufacturer. This entry is NOT intended to be construed as an endorsement of any particular model. Prospective buyers should carefully make their own enquiries according to their particular needs and circumstances.